That's interesting Michael, the torx ones have got me out of a fix on more than one ocassion as they are the only ones I have found in such small sizes.
For the record, my favourite flat balde screwdriver has a wooden handle, no name, and is probably as old as I am.
Posi and phillips screwdrivers seem to be hit and miss. When you get a good one, hold on to it!
Neil