britbrat,
I have this trainer and soloed on it last summer so I'm likely close to you in experience. 6 or so flights after solo i maxed my ailerons. but even b4 that I had no trouble rolling it. It wasn't pretty until I our club pres showed me the !QUOT!shallow climb and elevator input!QUOT! trick. Now rolls are nice. don't really need to climb if you get the elevator right. here's what he told me.

When wings go vertical (1/4 roll) start your elevator input so that by the time you're inverted you are at the max elevator you'll need to stay level, then you back off that input so that when you wings are vertical again (3/4 roll) you're off the elevator completely, then complete the roll. It's kind of a feel thing and takes practice to do it consistently.

As for inverted, my Superstar 40 with an EVO TPS will do it all day.

One thought. If the CG was way off and the plane was trimmed to fly well upright that way, wouldn't that CG problem cause major problems once the plane's inverted.

Also, I thought about sealing the gaps on my plane but the gaps seem really tight. Tight enough light will pass though in only a couple of small spots. Still worth sealing?