The test I did worked very well with one or two minor blips.
You must manually copy via FTP your custom avatars and attachments to the new XF directory structure before you start the import process. I can't remember what directories they have to go in, possibly /images/misc and images/avatars...
I saw that but I concerned by the term Beta at the end.
Beta in my experience usually means almost, very nearly but not quite, does what it's supposed to.
Can I do a clean migrate including attachments from phpBB 3.1.9 to the latest Xenforo?
I've had bad experiences with vB Impex, an absolute shambles of a piece of software, and I can't afford to be stung again.