They are A3 magnets so LOW output, brighter, clear, very tight low end, not a lot of harmonics, almost brittle until overdriven to get the harmonic distortion. I think if Heritage would have used A2s in the bridge, it would have been a very nice combo of clarity A3s neck pup and the push & mids of an A2 bridge pup. Since they both have A3 (just like the Gibson Custom Shop CustomBuckers), I found myself wanting just a "little more of everything" so I put a pair of Throbak SLE-101s (A2s in Neck & Bridge) in my Custom Core and BOOM... I got the tone I wanted.
I also have a set of the A3 CustomBuckers in '62 335 Custom Shop Reissue and they sound just like the Parson Street pups. So, the A3 CustomBuckers and Parson St pups are popular, they just aren't my cup of tea. I need to get some Throbaks for the 335 and sell both the CB pups and the Parson St pups.
YMMV