I don't. I found something that works really well for me, so I don't try to fix what isn't broken.
People make much too big of a deal of the developers and film they use. Maybe not what you want to hear, but no film or developer is going to make or break a photographic print. It doesn't matter that much. Just pick one that's likely to stick around for a while, and learn how to exploit it to your liking.
Its only me that is really unsettled with the choice of the developer for fast film(400 or faster).
I am quite happy with Rodinal(1+50) for slow film(APX 100 and PanF+) + Adox MCP 310/312 paper with a condenser enlarger.
Rodinal is little grainy for my taste with fast film even printing on (24x18cm). So, I am in quest to find something better(artistically it may have different meaning) than what Rodinal can deliver for fast film.
You might want to try Ilfotec DD-X. It has many of Xtol's virtues, but comes in smaller containers. It's a great developer. Kodak's TMax is very similar.
Xtol is a bit unique in the fine grain it yields, and at the same time extracts so much shadow detail while yielding sharp negatives, especially diluted 1:1.
How about this: Just use the developer straight or 1:1. After six months simply discard what you're not using.