Nate,
I have a Super Six with clipped wings (7" per side, same number of ribs in the shorter span...much like the HRII wings). What others have said rings very true (as you'd expect from this smart bunch!)
Concur with Smokey's recommendation to consult with Van's engineering folks before diving in. Proven concept on the 4/6 wing, not sure if its been done on an 8 wing.
My set up is slightly different than Smokey's, in that I have full size flaps and lost the span in the ailerons (guess that means Smokey would be trying to lure me into a rolling scissors, and I'd be pulling into the vertical or trying to drag him up into a flat scissors...eh Rob!

)
As far as performance goes, as was mentioned, the g limits remain the same with my higher gross weight. That was a key element of the design feature, from what I've been told. If you're not going heavy (big motor), not sure you need to go that route. If just seeking higher g limits, I'd also find out from the engineers if other parts of the plane will tolerate higher g (tail, etc). If you're just seeking more safety margin at max g...perhaps that's a valid reason...but I think there is a good safety margin there if well built and maintained.
I've found that the clipped wing g-limit-saving design feature does cost in high altitude performance. At Airventure Cup 2010, Mark, Wayne Hadath and I climbed to 15.5K, then Wayne went up to 17.5K. At 15.5K, Mark (with his EVO Wings) slowly walked away from me (at that time we were very evenly matched at SL). Wayne (with the same wing as me) lost even more top end at 17.5K and fell back, then descended. I tend to cruise at 12.5 to 13.5 for best effeciency...and that sweet spot altitude would likely be higher with stock wings. So I pay a little in specific fuel consumption there.
Flat tips will likely buy you some speed (mine added 3 kts, and upped the stall 5 knots); should add roll rate (as Bill said) but cost in highter bleed rates in a turn or vertical maneuver. I use the flat tips for SL racing with fewer turns. I'm intrigued by Bill's fences...if they preserve stall speed, that's a bonus (Bill, how are they at bleed rates under g, and did they add any top end?)
The good news on flat tips, is you can go back to stock, which I did for the turning races at Reno (still bleeds some there though).
Here's a few pics. First is Mark and I at Reno, me with stock tips:
Here's a pic of us at Macho Grande (Marks place near Taylor, TX):
Pretty stubby with clipped wings and flat tips, eh! Its a bit skewed because I'm a little closer to the camera in the first pic, and a little further away in the second, but it gives some perspective.
Just for fun, check out this tip design, by a guy here in Reno:
They are called Scimitar tips, and Eric's website is
here. Eric said they are optimized for turning...very little bleed under g. Would they work at RV speeds?...not sure. Eric thinks there may be some benefit. Bet I get Bob Axsom's juices flowing with that one though!
Finally, of the Super 8's I know of, I don't believe any have been clipped. Kahuna has those long-range tanks in his

, and I imagine standard-length wings keeps his maneuvering wing performance closer to that of the other Team RV aircraft as well. Kahuna, any structural mods to the wings, other than the tanks?
Interesting topic Nate!
Cheers,
Bob