Well we started development of a central importer into MyBB, but not much work has been done on that lately.
I don't create any gui stuff to my convertors before the "central importer" isn't public. I think they are easy to config.
Later when the "central importer" is done ... I think all convertors are transformed to the new style.
Also it makes no sense that many users work on a single convertor. some stuff I done on vb3.5 convertor (users & forums) but i can't update the state each day. I also had other things to do.
Second to write any convertor you need time. I think noone knows the internal of other boards. So many things to check.
Afaik my phpBB2 cache things after each steps done. But there a many things todo to get an realy usefull convertor. Many things which other systems don't check. You can try to find an conv. script which handles not activated users.
A vBulletin converter would be great!
Yeah I'm waiting for a VB convertor as well.
It's possible to do this by simply converting your vbulletin, smf, ect, to phpbb, and then using the phpbb > MyBB converter.
I don't trust that conversion method because (not only is it a headache and multiple extra steps) but phpbb doesn't support password protected or member permission protected forums.
There should be a VB-to MyBB direct convertor anyway. VB has one that goes the other way around.
vb 3.5 user passwords are incompatible with mybb.