I have a sparrowhawk and have flown several RAF's and have never experienced these stability issues mentioned. The sparrowhawk is certainly roomier but it's a lot heavier and not in my opinion as responsive as the RAF but I got it for the room. I might caution you about the weight however if you seriously consider the sparrow, mine was registered at 1500# so you can't fly it with a light sport license. Last time I talked to him Mike Burton was building a sparrow for sale and is an expert on them so maybe someone you could call if interested. For parts, whatever I have needed if I couldn't find it Mike could and the factory still has some parts available. Not to sound like a broke record but call and ask questions, Mike and Ron are both experts in these specific machines.