Just a quick note Nigel, I know the PS+ was really slow, but since the introduction of mplab7-> they have really tried to improve it, and done a good job!
If you select "Programmer/Settings" on the menu of MPLAB, you can tick/check "Auto select memory areas and range", this will only program the amount of the pic needed. A good tip is also to un-tick/check "Read all on auto select" this will then only verify the programed areas not the whole PIC, this really speeds up the programing process.
To be honest, I am amazed (and very grateful) that MChip are still putting so much effort and support into this old "war-horse" of a programmer, they get a big "thank you" from me, it has got to be, imho, one of the best supported cheap(ish, well for a major company anyway!) programmers out there!