Thing with P90s is that they have that extended high end compared to HBs....but also extended low end with a more defined character, in a way, compared to HBs. The more vintage you go the more you notive that.
I for one have 3 out of 4 P90s necks so I cant comment that much, but the magnet difference it the frontline here. Compared to HBs the magnet seems to come through a lot more in P90s.
The way I image a MQ bridge to be is bright, yes, but also with a defined and open bottom end that does not lack in the least. With the AV magnet I would not expect anything but AV character, but purer than most of the time.
If there is a kind of PU that makes the magnet difference clear it is a vintage wire P90.
Letīs grow the love for vintage and P90s. ;)