In this particular instance I would base that decision on whether or not I thought I needed the sfi rating( I think the ET break for an sfi damper is 10.99). I don't feel there is any performance advantage to either, but the sfi unit is made of better material and has a means of capturing the outer ring so it can't spin off in the event of a failure of the elastomer.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads