i know you can go between mq and amq with no probs but i may be wrong here but i think the pq was the only wet lube that panny makes i think i read that here long ago but i may be wrong. it couldnt hurt to run a tape cleaner for 5 secs before switching.
I switched from having used 5 AMQ to a few PQ with no trouble. I don't really use tapes that often but it should be fine (same lubrication system) But I won't dare any more radical tapechange without cleaning the heads first.