Here are a few things to think about....
1 - If you buy the DNA on contract, you will lose your unlimited data on Verizon. So if you're really gung ho on the phone, you'll have to pay full price. Ouch! But then again, it looks like an amazing phone, so it might be worth the full retail price.
2 - HTC is not so great about software updates. Adding to the fact that Verizon stymies the developers release schedules, then you have to assume that you will have to wait a long time for updates. But, it's a new phone so you are pretty much guaranteed to get JellyBean and hopefully one or two more updates beyond.
3 - It doesn't sound like you really need the nexus experience. Like Shocky said, you can just add a launcher on any phone and get crazy customizations without worrying about bricking your phone or voiding your warranty.
I hope this helps. Good luck on your search!