I’ve never tasted imitation maple flavor, but I can tell you with certain there will be a significant difference in flavor between imitation maple and the real thing.
I’ve also never used maple extract, but I have used maple sugar and maple syrup. In the sugar and syrup format, which I assume to be far less concentrated than extract, you need to use a large amount to get anything more than a subtle flavor.
If you’re kegging, I would start with adding a small amount and tasting the beer to see the impact. Do this until it reaches the level you want.
The other option is to dose a measured pour of beer with a measured amount of extract until you find the ratio you like and then scale up the volumes.
I agree with all of this. I’d also add that Grade B maple syrup adds a lot more maple flavor than the typical light- or medium-amber stuff people usually put on their pancakes. That’s what bakers typically use (I know; I can’t any of the Grade B stuff from my local sugar shacks because it’s already spoken for).
I find the smell of maple extract/imitation maple flavoring to be disgusting. I can’t even get close to one of those places that sell ‘maple’ creemees. the overwhelming fenugreek smell turns my stomach at this point. If you want to make a maple beer be prepared to spend A LOT of money on maple syrup unless you make your own. get the darkest you can. there is even a grade darker and more robust than that which used to be called ‘grade B Dark Amber’ but as eric says it’s hard to come by because it’s snapped up by bakers and processors. I go to 30% of the fermentables in a big barley wine and there is a lovely subtle woody character that is exactly what maple actually tastes like with all the sweetness removed.