Keep in mind I was comparing the PGn A4 with my *memory* of what the PGn sounded like with it's original A2. The A5 and A4 test was back-to-back. There was a big difference, with the A4 having a thick mid-tone, much like the original A2 PGn (I wasn't going for that thick middy tone, which I what cause me to instal the A5 in the first place).
As for A2, A3, A4, A5 -- remember, that those are just names. They have nothing to do with the magnet properites, and from I can tell, were derived from the order in which they were invented by metalurgists. I think the the fact that an A3 sounds somewhere between an A2 and an A5, with it leaning towards an A2, is just lucky coincidence.
If strength has any relationship to tone, then (from what I remember) the magnets would be ordered like this (I think):
A4
A3
A2
A5
But, people think A3 is brighter than A2...so who knows?
If