I have a Saito 91 in my 60-size Fun-Fly plane and LOVE IT!!! Easy to set up and I almost never have to touch the needles, just fill and fly.

However, this is not my "beater" setup. So, if you are going to use it for learning, go with the K&B61. It may be a little more difficult to set up and run (my K&B 40 is pretty sensitive), but you wont feel as bad if it gets filled up with dirt