you can use TMAX RS in a similar way as XTOL, but XTOL lasts a lot longer and it works a little better with more types of film. Kodak is pretty conservative with their capacities for both those developers. In replenished tank lines you can stretch TMAX RS out to like 4 months or so, some people go to 6 even.
there are 2 ways to basically replenish with these developers that don't require another replenisher. you can go the old school control strip/process control plots, or you can eyeball it. As posted above from the guy running the deeptank--you can't over replenish XTOL or TMAX RS. The trick is to start off not replenishing at all, or cut your development maybe 10-20% off the top, and replenish. The developer starts off fresh, and needs to be used up--like they use starter with E6 for example. with the b/w it will run hot at first. As it nears it's good state--seasoned--then start replenish. You start small, and then as the tank ages, you may have to start adding more etc. There's nothing wrong with using less, if your contrast & speed are okay.
XTOL is neat because you can basically just keep replenishing it and turning the tank over to a seasoned state for a long time. It gets dirty & sludgy--I used to drain the tank out every couple of months and strain the bromide sludge out, and then take maybe a liter or something out and add fresh. seemed to work. I like TMAX RS better though. don't like D76 replenished.
in my own darkroom I use TMAX RS in half to one gallon tanks, and when not in use for a time, I drain back into a container. otherwise I use floating lids on the tanks. I use RS for about 6 months and replenish at 45ml per roll. When I used XTOL in the lab at work and at home--I used 85-100ml. You can do about 80 rolls of 135/36 per gallon of TMAX RS. XTOL is pretty wide open.
btw--kodak has a tech sheet buried on their site, that details how to adjust the pH of TMAX RS to get longer times. basically addingt 10-20 ml per gallon of 28% acetic acid to both the working and the replenisher. This shouldn't be a problem with XTOL though. They also have their b/w process control guide online if anyone decides to run control strips. I used to do that--TMY was the stock for the b/w film, Ilford uses FP4 I think.
my opinions only/as always.