Have been using simple inventory and so far so good. Have not yet tried it with the new Beta release.
Did notice that without reports it is hard to tell home much inventory is remaining unless one looks at the uc_stocklevels table in the database. As a feature request it would be great if a report was generated displaying inventory on each item along with a way to change that inventory. i.e. make all items one, or increase only certain items, etc.
That can be done now, but a lot of folks do not like getting into the DB to make these changes.