I agree with you about the flash bridles that are not removable. I like a bridle to have a removable flash in case I will need it for a specific horse. (I currently don't use the flash so it just sits in the bottom of my tack trunk.) I hope I will not need to use the flash but I know I will have it if needed.To start with I had to look up "barcoo"!!
I prefer the english style bridle in general, perhaps habit but everything is adjustable and elegant. I'm not sure when things changed but you used to buy the basic bridle with no bit or noseband, although saddleries would sometimes do specials with usually a cavesson or sometimes a dropped noseband.
I really really hate this newish trend of all bridles being sold with a flash noseband, because everybody seems to think they need to use it. grrr
I like the look of (what you call) barcoo, or some variation on it but on the few occasions I have used one I've had issues with fit, some part usually doesn't, mostly the browband.
Good leather. Flat, maybe rounded browband (and matching cavesson - although I don't use one on Sonny). I can be sold on bling for the browband. Otherwise, plain & elegant.