I have the HMC-152EN, which is the PAL equivalent here in Australia. I know a number of other people are using the HMC-150, the NTSC version, on this forum.
I love the HMC-152, particularly the wideangle lens. The operational layout and functions are fairly well thought out. Haven't had mine long enough to find particular bugs or problems. I suggest you search the forum for threads with HMC-150 and you'll find more posts.
You'll certainly need to convert the AVCHD to work with it in Vegas.
I have chosen to move to Final Cut Pro on a Mac to editing AVCHD, it transcodes the AVCHD, as it imports, to Apple ProRs 422. But I'm using a Mac Pro for Vegas anyway so it wasn't a difficult desicion when Vegas wasn't good with AVCHD.