Seems to me that you have a garage sale frame with cheap parts hung on it. Right?
If you buy a Pista then you will have a new (but still cheap) frame with pretty cheap, though new and cheap, parts hung on it. At some point, sooner or later, you'll decide you want to replace things like the cheap wheels and the cheap BB and maybe the cheap crankset with nice parts. This will leave you with your Pista frame with nice stuff hung on it.
Seems to me that ideally you'd just knuckle up for a nicer frame right now and hang the cheap parts you already have on it. That way, when you replace your cheap parts with good parts you end up with a really nice bike that you love and everything is hand selected by you.