Definitely reflash.
While the stock Sprint TP2 rom was decent, I gained much by going to a custom ROM. I settled on EnergyRom Leo (Windows 6.5 build 21xxx with sense 2.5 plus landscape support). A couple of benefits I've seen:
1. Freed up onboard storage and cpu cycles by getting rid of Sprint bloat. For example.., Despite the TP2 being a quad-band world phone geared toward business users and winmo hackers, sprint waste space by preloading the NASCAR app on the phone. Nevermind that 99% of this phone's demographic could care less about NASCAR, sprint waste our space because it could potentially be another buck for them. And then there's cpu cycle / battery waste by services like CM Guardian and push internet. Custom ROM and a little registry hacking fixes all that.
2. I get windows 6.5 and sense 2.5, now. Not months from now, after sprint has mucked it up with their crap. And that's assuming they even decide to release it. They've gotta make support material for it, train their support people it on it, update the TP2 manual, etc.,.. before they will officially release it. I don't need or want them to hold my hand. I want them to get out of my way. If I wanted an expensive, nerf-walled garden, I would've got that ATT smartphone.
3. Most of the custom ROMs are pretty darn stable. I've only seen my phone crash, twice?, maybe. And it was from stuff I was messing with. And if there is a problem, I just come here and search. Odds are, that someone else has already had the problem and there's already a solution for it.
I, also, say go for it. You can always flash back.