And I don’t even know whether it’s good or bad if the stuff is in it or not 
First off: the gist of things is that 180c is a suspected carcinogen. If it were a confirmed carcinogen, it wouldn’t be an ingredient in food. One hopes.
Just saying it won’t kill you, unless you gorge yourself on it. In which case you probably get what you deserve.
Secondly: what’s the aim of using those syrups? Flavour? Color? Both?
Reason I’m asking is this: if it’s just color you’re after, make your own caramel, syrup or chunks, and add to the wort until you get the color you want. Easy peasy but not at all scientific unless you have some SRM-ing equipment (which I’m guessing you don’t but go ahead and surprise the pants right off me).
That whole “You’re gonna lose if you don’t use it” thing is just someone yanking your chain. Yes, you need good quality ingredients, but I’d wager any syrup/caramel you make yourself will dramatically outshine any commercially available concoction. It’s just impractical, and messy, and it generates smoke and whatnot, so a prepaid package sounds more appealing, is all.
So: what part does it play in the recipe? Once you get that sorted out, the path will illuminate itself.
It will provide exactly 15 EBC plus the flavor of raisins and dried plums in a Rochefort 4 recipe that will earn me a shiny star on the Homebrewers Boulevard Walk Of Fame.
I disagree, and here is why:
I can get any of the popular, commercially available and outstanding Candi syrup products out there for 6.95 or less per lb.
Factor in sourcing your own ingredients, chemicals needed and time spent doing trial and error experiments for the right combinations, coupled with the consistently and repeatability issues of making your own, and buying commercially far outshines making your own. And that fails to even consider the mess as you described above.
The DIY ethos has a place and is useful in many hobbies so long as you weigh the benefits/rewards against the material, time and effort expenditures against one another.
Hype or no hype, the CSI products are outstanding and consistent.
Also, despite CSIs gingerly veiled criticism, other manufacturers (Candico/darkcandi.com) are producing delicious syrups/sugars as well.
Ultimately one has to weigh the benefits vs labor for themselves. I’ll take a consistent, quality, off the shelf alternative every time.
Circling all the way back to the OP:
I would say no. I can’t imagine that the color of these syrups is being achieved through the use of a caramel coloring additive and I very highly doubt that if they did that the addition would constitute a necessary or required element of a good quality syrup.
I’m always ready to be proved wrong but I feel confident on this.
Can’t always factor time into the cost of a hobby. If this were he case, a 5 gallon batch runs over $200 by the time all labor hours are included.
That said, I’m not making my own Candi syrup either.
I’d wager if I had a year I couldn’t make something as good as the CSI syrups. And that’s aside from the time/expense argument. Those are killer syrups.
I only mentioned time effort expenditure because making your own syrup requires a level of trial and error that in my opinion differs from that of brew sessions.
Even if you remove that element, you guys are totally right: I just don’t think it’s worth it either.
If someone offers me a product that is outstanding and at or below the cost of me making myself, I can’t see taking the time to make my own.
Flavor, without a doubt. None of my darker Belgian styles tasted right until I started using it. And you’re dead wrong about homemade syrups being better than the commercial ones. Have you ever tried them?
I might agree with you if the purpose of a candy syrup is color and/or a general caramel flavor. That’s relatively easy if you’re really talking about making brewer’s caramel (common to older English recipes) rather than the candy syrups frequently used in Trappist/abbey styles. The flavor of the candy syrups is completely different and miles superior for those Belgian styles. I have experimented with every supposed technique to make candy syrups online and while I could grab one or two flavor components they were always lacking the richness and complexity of the commercial candy syrups.
If you could reliably make a Candi Syrup at home that is better than the commercial stuff, then we’d all be doing it IMO. I’ve never seen any recipes that even claim to be as good as the real thing on a repeatable basis, so it doesn’t really seem worth my time. If someone stumbles on a formula that makes a beer as good as I can make with the CSI stuff, then I’ll be buying a candy thermometer the next day.
Speaking of the devil: exBEERiment | Belgian Candi Syrup: Homemade vs. Commercial In A Belgian Quad | Brülosophy
But what to conclude from this? That one can taste the difference if one can taste the difference?
My opinion? Price it out. If the cost of DIY is anywhere in the neighborhood of the cost of commercial then it’s a no brainer in favor of commercial.
Not worth the time and mess IMO when the commercially products are cheap and available.
I make 1 gal batches so a $5.95 p/lb investment could last 4-5 batches for me.
This has become a purely theoretical discussion for me, at least for my next brew, as a flacon of D180 was poured down my letter box this morning 
The xbmt is good info - gonna keep buying CSI nonetheless. Not worth the time, dangerous chemicals, etc. ,to make something the MIGHT be close to as good. I think the darker ones get more complex, so I think 180 would be very hard to duplicate or get even close to. Just me.
If you read the xbmts with the mindset that their tasters are largely made up of people without distinguishing palates then that one in particular strongly supports that paradigm because once it broke down to people who claimed to distinguish they were extremely accurate.
I can get on board with the idea that one can replicate the 45 SRM syrup at home in this manner because it tastes very similar to a simple brewing caramel. The 90 is a little different–at least from CSI–because it uses date sugar. I don’t think it can be easily approximated with beet sugar or corn sugar alone and even using date sugar in the normal homebrew recipes I doubt turns out close enough. The reports of mushroom flavors is unsurprising to me. Any time I tried to get into the 90 or 180 range I always got weird earthy, vegetal, or meaty flavors.
The 180 is the most mysterious product and I’m still a believer that there is more to that product than refined beet sugar and water.
What I got from it is that tasters could distinguish the homemade becasue it wasn’t as good.
Beet sugar, date sugar, water and … ammonia caramel
That maybe not everything I say about beer and its comprising ingredients is complete malarkey?
Except for the few absolutes that Denny has pointed out, we are all just speculating.