Ok that makes sense. Thanks.I think if you do everything carefully, a hard reset isn't required. This means being patient during install, and checking the new store for updates before cruising around new features.
That being said, there seems to be a nasty bug in build 10149 were hard resetting can brick the phone due to continuous looping. Doesn't seem to happen to many, but there's quite a few posts on the forum about hard resetting failing and needing to roll back to 8.1 using WPRT.