Correct me if I'm wrong, but Sense 2.5 only comes on a custom TP2 ROM at the moment, right, as opposed to any stock ROM on a TP2...or at least that's what I thought.
If that's the case, I'm using one as we speak (TP2 w/ Juicy R2 Sense 2.5 ROM). As it happens, we also picked up a Hero today for my wife and I have to say, and I can say this now having played with both, that the Sense UI on the Hero is cleaner, smoother, and more customizable than that on the TP2 custom ROMs at the moment. You don't have screens you can customize on the TP2 Sense UI, just a predetermined number of tabs e.g. home, calendar, weather, stocks, messaging, etc. You can add Max Manilla into the mix and that actually allows you to add more shortcuts on the home tab, but it's nothing like the 7 totally customizable pages on the Hero. That reminded me of SPB Mobile Shell all most. Poppy likes!
And I was impressed with the sheer number of free apps.
And finally what has always kept me coming back to the more popular WM devices (Mogul, TP, TP2) is the following and customization on places like PPCG. I had a Treo Pro early on but hated the fact that the PPCG forum had such a small following / # of posts on a daily basis (I realize that's changed somewhat these days for that particular model). But I see the Hero is off to a great start and already has a large following. This is a plus for any 'geeker
Just my $0.02.