Pyrocat-HD will definitely increase negative contrast at 2:2:100. I use it fairly regularly to produce negatives for pt/pd printing.
But you are also developing to a higher density as well so a longer development time than would be needed for a normal negative at 2 + 2 to 100. I do or rather have used this dilution when tray processing 10x8 negatives to cut development times while working in the dark.
Pyrocat HD at 2+2+100 also increases grain, to the level you get with Rodinal. Not a problem with large format, but it could be with 35mm, depending what you want your prints to look like.
Alan
Rodinal is capable of producing incredibly good fine grain with films like the old Agfa AP/APX 100 & AP/APX 25 as well as Tmax and Delta films. This comes back to the OP's question of what are good and bad combinations and sometimes we need like for like comparisons.
David M & I has seen the late Peter Goldfield's large prints made on 35mm AP100 and possibly APX100 processed in Rodinal, superb fine grain, sharpness, and tonality. I used the combination myself for nearly 20 years 35mm, 120 asnwell as LF, you have to remember that Rodinal was Agfa's recommended developer for AP25 and AP100, and later APX25 and APX100, Peter found it was equally as good with Tmax which hadn't been around long.
Rodinal may not be as good with FP4 and wasn't recommended for HP5 and similar fast films, but I haven't tried either, however both are superb in Pyrocat HD as are Delta & Tmax films.
In mentioning like for like I was meaning perhaps comparing ID-11/D76 at 1+ 2 with Xtol at 1 + 2 because both of these developers will behave slightly differently compared to use full strength and replenished due to the different dilutions.
Ian