The custom_title limit should actually be 50, rather than 44, so I'm still not certain where that's from, but changing it should be trivial.
So trivial, in fact, here's a little add-on I just knocked up.
That increases the user title limit to 250 (which is the same as vBulletin, I think).
We've mostly steered clear of making it too long because we feel that a user title shouldn't particularly be very verbose. After all, it's a user title, generally for short and witty sub-titles or job positions etc. 250 seems very long IMO.
What we do have in XF which I feel is more appropriate is user group banners. You can see the "Staff member" one under my user title. These are 100 characters each, but also a user can have more than one.
You could have a "Member of the month" user group, and that could display a "User of the month" banner under their user title. You could have a "Photo of the month" user group, and that also could display a banner. If a member is a member of both groups, then two banners will display, similar to this:
They can have different colours etc.
So that might be a better approach, but I appreciate you will likely want to get it working as it was before, in the first instance. Hopefully that add-on will help.
You'd be able to fairly painlessly export the titles from VB to XF as long as you still have the VB database.