Owned a fair few of the various Imperials. Here's my take:
1) Normal Wind Bridge: In most cases and most guitars, HARSH and bright as all get out. I couldn't stand this pickup in any of my set neck mahogany guitars, it was absolutely not the sound I wanted from that type of guitar.
Where this pickup does shine though is in the bridge of an HSS strat. It's brightness and high harmonics mix well with the single coils, and it doesn't give that "just switched guitars" effect when going from the singles to the bridge.
The same "sounds sort of like a strat bridge pup" thing that makes it work in a strat makes it untenable in other guitars, unless you want your LP bridge to sound strat ish.........
If you adjust your tone so that this pickup sounds un-harsh in the bridge, anything but a bright single coil in the neck will sound like the amp is burried 3' under your front yard.
2) Low wind bridge: same as above but liked it less in strat bridge.
3) High wind bridge (A2 stock): One of my least favorite pickups ever, and I've had a lot of pickups. This pickup had a weird thing going on in the high end that fought pick attack in a severely annoying way. Worst feel and touch of any humbucker I've ever tried. A5 would probably serve this pickup VERY WELL. I've played similar A5 winds I liked a lot; I'm really not a fan of what happens to feel when you start over-winding and using A2. Terrible.
4) Normal wind Neck: The best "PAF" neck tone I've ever heard. Not tubby in the lows nor bright in the highs, it is definitely in the standard PAF neck sound territory, but is has the most complex and interesting tone of any neck pickup I've ever heard. I'm into bright, single coil-ish neck pickups now or these would be in all my guitars.
5) Low wind neck: Fantastic clean jazz tone, but got somewhat dull sounding with any gain applied.