Good advice by all posters to follow . An intermediate low wing is your best bet. A 30 size Cap sounds small enough to be a real hand full.

But there is another method to help with the transition to a more high performance plane. Gradually move the CG back on your trainer (to a limit-not too much) and gradually increase the control throws. You will see you have a completely different aircraft. This will help you to get used to the quicker response of the Cap. But don't stop there. You can gradually add more weight as well to simulate the added wing loading.

When you get to the point where the trainer responds not by moving the sticks but just by thinking about it, you can start to think about flying the Cap. Of course the Cap will still fly differently but at least your reflexes will be up to the task.

After learning to fly with my little three channel Kadet Jr., I made these changes and none of the "instructors" could fly it. "Way too touchy!!" I got used to it and every plane I've flown since has seemed gentle as a trainer no matter what the type.