Do you live in a Sprint 4G area? If not, be wary of Sprint 3G speeds, they are slower than Cricket in a lot of places. As always, that varies wildly depending on where you live. If you're going with Sprint, why not get the Epic Touch? I do like the size and feel of the Photon, is the bootloader locked? I think the only phone I could live with for 2 years would be a Nexus phone. No playing the waiting game for updates. Even the Nexus One still gets updated. Also, you probably already know this, but just in case, be aware that Sprint recently changed their policies. The ETF went up to $350 from $200, and their return policy is now 14 days instead of 30. Great thing about the Photon is it's supposed to have very good reception compared to most phones. Best of luck with whatever you get, K-Man!
PS- just wanted to add, don't forget about the flood of iPhone users that will soon be hogging bandwidth on Sprint. (of course, it won't be a problem for 4G, since the iPhone won't have Wimax.)