What is the concern about a bleed-off type gas block? It seems that would be similar to a FAL.
It's not a concern so much as just a dumb way to do it. Bleeding off gas that would otherwise propel the bullet is unnecessary and inefficient, and as for bleeding off gas after the bullet has left - why bother. Just restrict it at the gas block and you have all the same advantages. Too much marketing in that one, not enough understanding of how the system really works. IMO
To the OP's question of what gas block to use, I've settled on the Seekins lately. (There were some cheaper no-name versions of the same design available for a while, but no longer.) The Seekins is basic but does a good job of metering gas, and is side adjustable. It can be had for $50-$60.
The front adjustable gas blocks are a real pain with a lot of handguards, unless the gas block is right at the end of the handguard; you have to use a special long hex wrench to access the adjustment, and if you lose that wrench, you'll be taking the handguard off to adjust it. Even with the long wrench, you generally can't turn more than ~3/4 turn at a time because the barrel is in the way. The side adjustable models on the other hand, might require a small clearance hole drilled or machined in the handguard, but once that's done the adjustment can be accessed with a regular hex wrench, and turned in full revolutions.
