If you have the money, then the 1.25 is a good choice as it is an easy engine to learn. After pricing some OS parts the other day, I have to agree with Dave about the parts issue and Magnums. When something goes wrong, it matters!

Any YS will not be economical with parts, or the fuel with high nitro content. I don't think I would recommend a YS as a first 4 stroke engine to anyone.

Jim is right about the Saito 1.00 too.