Greg,
I have used 35mm HP5+ with Pyrocat HD recently. Films were exposed in sunny conditions. What worked best for me was rating the film at 400, and developing in 2+2+100 pyrocat for 10 minutes at 20 degrees C. I agitate for the first 30 seconds then give one slow inversion every 30 seconds. This gave nice easily to print negatives.
That said, HP5 is not my favourite 400 speed film. I can't get real highlights with it, in pyrocat,divided D 23 nor ID 11 1+1. I've been using it alongside Tri-x and fomapan 400recently, and in my opinion these films beat it hands down both for highlights and general overall contrast and punch. I find the fomapan outstanding. It has become my favourite 35mm film. It is slightly more grainy than Tri x and HP5, but I like grain.

Alan Clark