I'm probably going to get blasted for this, but I'd say if you've got flying experience with a Zagi, you could skip the trainer step, probably. Talk to an instructor and go fly your zagi with him and see.

I probably wouldn't jump straight into the cap, though. Low wings aren't impossible to fly, but they are definitely harder than the high wings, to take off and land, particularly with a tail dragger. Got to where I can do touch and go's in my sleep on the trainer. Then, got on Realflight at the LHS and tried a low wing and it took me about an hour of crashing before I could put the low wing tail draggers down consistently without problems. Once in the air, there really isn't much difference. But a cap is built for aerobatics, which means its unstable by design. I've put many a virtual cap into the ground, where the slowpoke, or four star float around much like the trainer.

So, I'd suggest building a Sig Four Star 40 or 60, Tiger II, or maybe a GP Supersportster. They're fun to fly, don't look bad, and would give you a nice progression to prepare for the cap. Just use an instructor when you first start flying it and you'd be find I'd think.

But again, I'd just go talk to and fly the zag with an instructor and see what he thinks.

Good luck,
Heath