Each of the 42 steps required between 15-40 clicks (I think 40 was the largest one and that was the 3.0.0-gamma step)
Remember, I scripted the thing and timed it the first time we did it so that Urb could do the graphics work and we would have an idea of how long the board would be down.
I've never done the phpbb->vb conversion, I will ask that client who they used to do it. I think it took a few days to get it 'right'. phpbb really isn't too bad in 90% of the cases. And both had exploits (different methods) around the same time, so, if you're moving for security reasons... you're making tradeoffs.
What you need to do is figure out WHY you want to switch, and figure out where the problems are, and then figure out if it is worth moving. If it is performance, mysql might be able to be tuned (the defaults are absolutely horrendous). If its features, then you don't have a lot of choice.