I've done some moderate testing of ISO ratings for 3200 and HP5+, but haven't gone as far as pushing HP5 into 3200 territory.
For what it's worth, I've found 3200 acts a little more "normal" as far as contrast goes, around 1200-1600 (as most others have). Maybe push the development a bit for more contrast.
And I've found HP5 to have much more image clarity at 800 than the 3200 shot at 800-1200 - much less of that popcorn grain, so things like small text in test shots were more legible.
I'd guess if you're shooting 3200 at 2000-3200, you may get better results than HP5 pushed that far. If you're shooting it lower than that, it may be worthwhile to A/B it against HP5. I generally find that sort of testing teaches me a few more things than I was looking for, and I'm like "Don't bother me honey - I'm scientifically testing film - I shall make love to you in a bit".
BTW, you can do a whole lot of exposure and development testing with 35 roll film. Shoot 4 brackets of a static and repeatable still life (leave it setup, have something with highlight detail and something with shadow detail, IE a styrofoam packing chunk and a dark flannel shirt), advance the film, open the camera back in the darkroom (or bag) and apply a little tab of blue tape in the center of the frame, advance it, shoot 4 more, rinse & repeat. When the roll is done, don't rewind it - open in the dark (or bag), cut away the cassette, unspool it from the camera's takeup reel and cut it at the tape tabs and stick the pieces in a light tight container. Stick a cutout section on a reel (4 frames is just right to be stable in a stainless reel), develop, inspect, and then try a different time, agitation, or developer on the next piece. You can learn approximately a shit-ton about how film and exposure react to your shooting style and development process.
