I bought a slightly used Alpha 40 to learn to fly (still learning and reparing the broken nose due to battery failure). I have flown it with as few as 6 rubber bands and usually with 8, and have had no problem with the wing lifting up...not at least that I could see. It's flown great. I've used the bands more than once, but not if they tend to stretch more than when new. It could be that the brand I'm using (Hobbico) may be better than the office supply type. Even with 6, I can hardly move the wing upward at all.

My stock landing gear tends to flatten out and I had to keep rebending it. I finally replaced the main gear with the same type. My nose gear seemed to be too short and the prop kept cutting the grass. I bought another a little longer, but it was too long and I nad to cut it down some. Now, I have just a little more height on the nose and it still takes off normally.