If you are going to SBR - spend the money and get an integrated one. For non-SBR it's better to go K setup. I've had both, and like them both.

Some points to consider:
The integrated gas blocks need a different sight adjuster than normal FSB's.
Dropping one of the two does decrease front end weight - a problem on most AK's.
Bulgarian blocks won't work on Russian rifles and Russian blocks won't work on Bulgarian rifles - without other work as the gas port locations are different.

If you are going to get integrated however, stick to proven blocks like an original over a Bolton. The Bolton ones had really bad problems moving around until they started bolting AND pinning them. It's still not a risk I would take. The Krebs ones are interesting because they are press fit like the originals, but are "upgraded." I wouldn't turn down an original Krebs.

For me it comes down to SBR or not. For SBR it's worth the hassle to cut down another inch of barrel, but for non-SBR it's not worth it.