The Yak will definitely get you started.
my sons are just starting out in IMAC and I let them use my 90 sized planes (Yak and Edge) for practice. I don't let them use the large gassers for practice very often because of the quality of the field that they usually fly from (The runways can be a little rough at times).
I think that using a smaller plane to get started and for practice is a better idea, If you can keep a smaller one straight and smooth, it's eaasy to do it with a larger one. (I'm sure that there are others who will disagree).

One thing is for sure, If you don't get started, you'll never know. I say go out, do it and enjoy. The cameraderie at Imac style meets is great and you'll be amazed how much you will learn.