You won't regret it. As you said, there's more frequent maintenance but top ends are pretty cheap and very easy to do. Everything about the bike is about 2-3x easier to work on than the Aprilia.
The first time I rode the TZ the thing I had the most trouble with was not having a bike that would idle. On top of that I was jetting way too rich and the bike wouldn't pull smoothly out of a turn. Hell, even Cakes blew by me at VIR
But my god, the first time I pulled out of the pits and hit the powerband, I was thinking "holy shit!" Even jetted poorly it was keeping up with 600s in the straights. And soooo much cornering ability.
You gotta slip the clutch pretty good to get going too. There are at least four guys who ride with TPM with TZs now. I can't wait to get us all out there at the same time. Then I'll hop on the 125 and school you big bikers.