The best 60 size trainer is the Sig LT-40. It's a 60 size plane that flies well on a 40. I have seen and flown many TT-60's for students. Many have been good and a few have been bad. We lost one from the fuselage being drilled out several times (at the factory) for the wing dowels. It wasn't obvious until the fuselage failed. Another one had almost no glue in the fuselage formers. It had to be taken apart and glued. It seems the quality is inconsistent at best. I used one of the 40 size as a club trainer for over 2 years. After over 400 flights the covering was destroyed (simply worn out). It has now been recovered by a club member and will fly again soon.

EXCAP232