Actually there is a much bigger jump when you go to the 80cc size. Dual aileron servos with matchboxes for starters. The kits tend to cost a lot more as well. The same equipment is used on the 78" planes as the new breed of 84"+ planes and the extra cost is about $200 average. On a plane that will end up around $1500 that isn't a huge differance compared to spending $1300 for a smaller plane with heavier wing loading.