i don't own either wing (i'm using a mach v razor 30 instead), but i'll give you the standard answer and others can elaborate:
Hey 2 questions about this wing...
1. How big of a difference is there between the regular Mach V and the Extreme addition? Is the toughness of the regular wing not sufficient for most people or is the Extreme that heavyduty? What conditions would say the Extreme is more of a must have than a luxury?
regular mach v is among the toughest wings out there in comparison to other brand wings, but mach v extreme is significantly tougher.
regular wing toughness is fine. the extreme material is just a luxury for people who like the cool factor + a little extra peace of mind because even regular wings break sometimes. the extreme material is not a must in any normal dive situation, but aside from the cool factor, it seems most appreciated by technical wreck divers because their wings sometimes brush against sharp metal underwater. the rxtreme material is also lighter in weight than the regular stuff, and doesn't (or didn't used to at least) have the oxycheq brand written on the side with big yellow letters.
2. What is the size difference in the #30 and #40 when it is not inflated? Is the difference going to create a noticable amount of drag?
Thanks for your input!
if the difference manifests in greater wing length, then it adds virtually no drag assuming you maintain good trim while moving through water. however, i'm guessing 30# and 40# wings are the same length, but the latter is wider, so yes it adds drag. even if the wing's inner bladder is empty, the outer shell is still flapping in the breeze/current like a piece of cloth you stick out of a moving car window (except for the crazy flapping). big cloth = more drag.
also, bigger bladders may require more effort to vent, at least when there is only very little air left inside. for example, image you have enough air in the wing to create 6# of positive buoyancy. that is, the smaller wing would be 20% full, the bigger wing would be 15% full. Suppose a bubble/s that takes up 15% of the wing don't automatically reach the rear dump valve (say they are stuck higher at the sides of the wing, or on the other side), then you need to tilt head down enough to maneuver the bubble (or some of it) below the rear dump valve. obviously a 20% size bubble is easier to move around than a 15% size bubble. and same logic applies even if you use the power inflator...
ok, so that's the theory. in practice you may or may not be able to tell any difference between the two wings. both have a very streamlined design so any venting/drag issues should be minimal, but as i said, i haven't used these wings so take my reply fwiw.
