Is the TT40 a Pro or GP? The Pro is a better quality engine than the GP. The Pro should have plenty of power for the Mid-Star but the GP depending on how hard it has been used in the past maybe a little sluggish. I used a TT 40 Pro on a Four Star 40 and it did a great job of pulling the plane around. I do not think you need to worry about the speed or over powering this model. I believe if you do as you plan next Spring to get a few flights on the trainer then get some air under the Mid-Star you will find you know more and your flying skills will be better than you think. You should find the after a few flights how much better the Mid-Star is flying than the trainer. Have fun.