Not Just Xtol....
Tony,just thought I would add something else for you to think about. This weekend I shot some FP4+ 4x5 and developed it in a soup that was Pyrocat-HD with Rodinal - 1+1+100+.5 of Rodinal, for 30 min. stand developed.
Now, I based the time on the 1:100 dil of Rodinal I use most of the time, and the negative is quite dense (meaning that it is a very dark negative, while does have a great deal of detail, the overall negative looks dense - as have stated before, don't know what a true dense negative looks like, just know this one is not thin).
Also, as I suspected, the stain was not as pronounced. Have not printed the negative yet, but will let you know how it looks.
Seems like the dilutions I have seen for RodinalX was for standard dilution of Xtol + something like 2 ml of Rodinal.
Good luck and let us know how it works out.