I shoot and have shot 2-1/2" Bi-Delta vanes for over 20yrs and love them. They at one time held the broadhead worlds longest shot record. I shoot them with my 100grn, 1-3/8ths cut GrimReaper broadheads out to 50yds without a single issue.
I glue the insert with the broadhead inplace and align the vanes with the blades. They shoot great even with 3 and 4 blade 100grn Muzzys.

From watching high speed videos, the standard 4 inch vane starts to fold over while arrow is spinning. This causes you to start to lose some of the air catching ability of the vane. The blazers do not seem to do this. Thus you have a smaller profile doing the same work as the larger vane. Blazers are slightly taller than the normal 4 inch vane so you need to make sure clearance is not a problem. Also, you will probably pick up a couple of feet per second. I switched to blazers about 5 years ago and they have been working great for me. I shoot the 4 blade 100 grain slick tricks with them. HD.