I think that no matter what the prisms are, the main difference you'll see in cheaper binos may refer more to the lenses and what kind of eye relief you'll find. Off-axis performance usually suffers the most--or in other words, you can as much good off-axis performance as you wanna pay for in any binos. One good thing I've noticed is that, even in cheap binos, it's easy to get a pretty wide field of view. My Tascos have something like a 70° apparent field of view. I just can't see it all unless I remove my glasses due to their short eye relief. But they are very easy to look into. No blackout/kidney bean effect like you find on some binos that have too much eye relief (which, surprisingly, is the case with my more expensive Celestrons--I have to twist the cups out some to prevent it, which in turn shortens the eye relief some, but not too much).