Must admit I don't see the fuss that people have with cans. It's now entirely up to your MOT tester what he'll pass, providing of course that the can doesn't have "race use only" stamped on it. I've had some pretty damn loud bikes over the years, and as most of my MOT testers have been sensible types, provided I stick the baffle back in before I go they're absolutely fine (the proper type of MOT tester that isn't fussed about slightly smaller plates and aftermarket exhausts, but instead checks the important bits of the bike that actually make it road worthy).
Only bike I've ever had that I thought I might not get through an MOT as it was SO bloody loud was my ZX9R, it started off with an SP Engineering tri oval stubby with a removable baffle - I used to run it without the baffle as it had been jetted to suit and lost about 8hp with it in, but that was loud. Stuck that in for its first MOT and it went through as the baffle was in, although the MOT tester did ask me to take it out just so he could hear how it sounded without! Then got the chance to pick up a full akrapovic racing system for it off eBay, with one of their race (no baffle fitted) cans. It did originally have a "not for road use" strap on it, so took that off and fitted a blank, then took it to the MOT centre to get it checked out (can was also slightly cut down, so by god that roared), and he said as it didn't have a baffle fitted as standard, but wasn't marked "not for road use", it'd be fine!
Just depends where you get your MOT done to be honest, I'm of the opinion that get whatever you like the sound of, and just find an MOT tester that isn't a bit of a nob!