Two piece wing (I see a lot of people asking how to fit "gassers" into ther smaller vehicles)
No flight surface scallops (Experienced builders can easily add them, new builders may have difficulty covering them)
New style rudder (Easier for those with limitied covering skills to cover it)? 0% (0)

Lite-ply fuselage (Only if it adds enough extra strength over Balsa)
Lite-ply ribs (will be stronger - nothing more demoralising than building a kit then damaging a wing with a minor bump)

It would also be quite important in some countries (Like Australia) for it to build very easily significantly less than 7kg. We have "heavy model" rules here that kick in at 7kg. If it could build under 5KG (there's a challenge for you) - it could be used in some pattern events to encourage "newbies" to have a go. (Yes, I know the wingspan is outside the 2m limit - that is another consideration I guess)

I love my Stick planes and apart from your kits, there doesn't seem to be much choice out there for the larger ones these days.