RE: Do I need to move on?
I just finished reading this thread from start to finish, chopper man, and I was surprised that:
A) You felt your O.S. .46 LA was underpowered for this plane
B) That the Tower Trainer .40 wasn't aerobatic enough to learn new manuevers
It sounds like you're getting things spiced up by enhancing your control throws and sealing your control surfaces. This is a great place to start. I'd also like to see you try a few different propellers to see if you can get more thrust out of your .46 LA before you go changing engines around. Your 10x6 prop is probably allowing your trainer to fly quickly when it's straight and level, but your vertical lines and loops might be easier if you try a prop with a bigger "bite" to it. An 11x6 prop from a couple of different manufacturers would be well worth the cost, you'll be surprised at how differently a plane will fly simply by switching out the propeller.
Adjusting the center of gravity (carefully and in small increments please) rearward so the plane is less nose heavy will also change its responsiveness. My Tower Trainer is fairly agile despite being nose heavy, however, so you don't need to turn your trainer into a finicky, twitchy beast to enjoy aerobatics with it.
I have a Tower Trainer .40 MkII ARF that I fly, and I've been amazed at how nimble and aerobatic it is for a flat-bottomed high wing trainer. I have a lot of fun flying it inverted and doing loops, rolls, wing overs, Immelmanns, and Split-S turns with it.
Good luck, and let us all know how you're progressing.