You're great! i dont know nothing about market but it is not so easy to update market version? I know earlier about lack of adding email to existing account but.... forgot about it ))
I don't update Market / Play with dev. builds, just to make sure new code gets some testing (on my and my users devices).
From a user's point of view, Market / Play will post a notification when there is an update -- including for my app -- when I update there.
My development builds are signed with the same digital key as my Market / Play releases, so:
1 - They can be installed on top of the version from Market / Play, keeping data and settings
2 - Market / Play will post an update notification when I release a newer (than a test) build to Market / Play
Now, dev. builds may have bugs
so I recommend installing them if you're looking for a specific bug fix or to test drive a new feature before it's frozen and released