I worked on trying to make a perfect modded versions of phpBB for about a year. Bilingual & cell phone campatible. Put several sites up. Hacked within a month even the not modded versions.
Hackers specifically search for it.
I changed to SMF before upgrading my site to vB. Only problem I had with SMF was it wasn't great out the box with Search Engine Friendly URLs. I used it for about 3 months then imported the data & users to vB no problems & no data was lost.
If you are going to make a site you may upgrade limit the mods you install.