All I can tell ya is that my 1.104 quad didn’t throw more krausen than the 1.054 Patersbier I made to start the yeast for the quad.
Leave to actual experience to ruin a perfectly good theoretical argument.
Sorry to bum yer trip! ;) But it sounded like you have actual experience, too, that contradicted mine.
I always see a small increase in krausen with heavier beers, even with the same yeasts.
Less of a side by side, just was always impressed by the amount and length of retention of the krausen in my Belgian dubbels.
I brew a Belgian White and a Belgian Tripel very regularly. I fill a 3 bbl fermenter to about 85 gallons. With the white (a 1.050 beer) the krausen often hits the top of the fermenter. With the tripel (1.080 beer) the krausen never gets higher than 5 or 6 inches or so. Same yeast, pitch at same temp. So, go figure!
Good point. I not also see more, but it stays around longer.
They are still making 5 gallons worth of expense, just boiling it down further and then adding the additional water later. No cost saving there. If its money then just cut the cost by 1/5 and make 4 gallon batches.
That was in response to the those who said to just go out and buy a bigger fermenter.
Yes, you could do a cocentrated brew. But if this is really about retaining the blowoff while using the same batch size and same fermenters, you could capture the blowoff in a sanitized reservoir, itself equipped with an airlock, and then later pour the captured blowoff back into the fermenter. Kinda like the reservoir on some car radiators.
And I was agreeing with you. Everybody probably drinks the same amount in the long run but short term 4 gallons worth of ingredents will save a little. Might even save enough to get a bigger fermenter 
That would work. Sorry, I didn’t catch where you were going with that. :
Re: Bigger fermenter argument. You can get a 7 gallon bucket for pretty darn cheap and they have their pros over a carboy. Granted, they have their cons too - but decidedly less IMO. I was one of the most stubborn SoBs out there to give up my carboys. I’ve switched now entirely to Better Bottles and Buckets or stainless. No more glass for me.
In a roundabout way, kind of like what the Burton Unions system was about too, no?
Something like that, yes. But without separating the yeast, although I think I’ve seen similar setups for doing that as well.