Let the hive mind of Engadget get that for you.
"I just switched to Sprint from Verizon about three months ago for the Pre. Then I went for the Hero about a week ago. Now, I miss my hardware keyboard and am thinking about switching to the Moment. I am still able to switch back to Verizon if I want and get the Droid when it arrives. Should I just trade up to the Moment when it comes out, see if I like it, and if not switch to the Droid? Or something else entirely? Help!"
"Apps will also be tested for memory leaks .....things many current third-party WinMo CABs have issues with."
Winmo ITSELF has a lot of issues with memory leaks. 6.5 will be a welcome change from 6.1, the number of times I had to restart my phone to reclaim some lost memory was ridiculous.
What that means is you will be unable to download Windows Mobile from the market place, since it wouldn't be able to pass the test.