3.2 has no sai, egr valve, iac valve, no throttle cable or cruise controle box and cable in the engine bay. All replaced by more advanced(or should i say up to date?) engine management with drive by wire throttle. Not sure on the changes on the previous model years, but 3.0 will have most if not all of the above to replace/clean/blank off/ or unplug.
3.2 also does away with the dis pac and ht leads in favour of a single coil pack per bank, which is far easier to replace but more expensive to buy if it goes tets up i beleive, i've not had to replace one so far so not aware of cost. Less gubbins generally in the engine bay, which is always good when fitting lpg.
Oh, and the pedal trick rather than paper clip test, easier to do, more comprehensive list of codes and WILL tell you which pot is missfiring! Unlike the 3.0 ecu which probably wont even notice if its lost a cylinder.
Plus being younger, 3.2 hopefully will be in slightly better nic. If you can find one, i guess it will cost more to buy as well though?
A pita that goes against the 3.2 is the pre cat issue, which also affects the 2.6 and 2.2 to a lesser extent. But in real terms the only real annoyance with that is the engine light constantly lit on the dash, but there is a fairly(?) cheap fix.
Hth the op. :-)