Voodoo Lab

I have a modded Ibanez TS808 from Analogman.
They suggested I use a 12v adapter to give the pedal a little
more "uuumph!"...I was assured that the 12v was well within the pedals
limits, even though they come with a 9v adapter.

so...

Would it be ok to flip the dip switch to 12v on my PP2+?

As long as the pedal can handle 12V, it should be no problem to set the Pedal Power output to 12V for this pedal.

Should be fine. Most analogue OpAmps will tolerate voltages up to 24V with a dual polarity supply. It is really Digital Logic chips you have to worry about, which have more stringent voltage requirements. To be honest, in a pedal like a tube screamer, the advantages of a larger supply rail is mostly lost unless the clipping circuit has been scaled to take advantage of it.