I recently wrote a long blog comparing the two top online model kit stash managers, My Hobby Info and Scalemates. I compared them on features, utility, ease of use, and a variety of other criteria. If you're interested, you can read this blog at: http://barnettoutofthebox.blogspot.com/.
In a nutshell, I found that My Hobby Info (http://www.myhobbyinfo.com) was created to serve as a stash manager - it's what they do, and they do it well. Scalemates http://www.scalemates.com/ was created to be one feature of a full-featured modeling community, a "Facebook" for modelers. As such, the stash