Im by no means an expert and my experience is minimal when it comes to darkroom work.
But I shoot almost exclusively ilford film in 35mm and a majority of it is HP5. Ive found that HP5 gives me marginal negatives when pushing to 800 and developing in TMAX, Ilfotec DD-X, and D-76. honestly Ive never gotten "great" results from any attempt at it.
Although Ive gotten fairly good results with delta 400 pushed to 800.
not sure if that will help but I just thought I would share my experience so you know you arent completely alone.