I've owned the Twist .40 and I now have the U-Can-do .46. Both are very forgiving on low rates and extremely maneuverable on high rates. Both of mine have/had OS .70 4-strokes. I've also looked at the Sig Mayhem. It looks like a great airplane. The best value of the bunch is the Twist, you can pick one up for $99; that's hard to beat.