Welcome to the family, Bill!
Hmm, not sure what benefit the hot water bath would provide for pastrami, if any. It may even be detrimental to the overall finished product's flavor...don't know. I guess the theory is keep it moist and hot for a longer period, and then eat it straight out of the water bath (haven't seen the TV show, so I'm guessing here).
For my best pastrami smokes, I have smoked on open grate to finished temps of ~160-165*, then foiled and rested a bit. I have also smoked to 140-145* on open grate, then foiled and took to finished temps, then rested. The foiling will at times help with interior moisture in the finished pastrami (depending on your smoke chamber humidity), and it will reduce the formation of bark/crust on the surface. I've also found that taking the internal temp over the 160-165* range can create a drier pastrami, and it's nearly impossible to get that moisture back into the meat once it's gone, even with a sliced reheat. I like to chill well before slicing, but have eaten it straight out of the foil as well. It seems that it gets more tender after a steamed reheat, though. It likely has to do with the internal temps passing through the melting-pot temps (connective tissue's melting point) a second time. A good method for steamed reheating is to place the slices on an elevated grate in a covered roasting pan @ 225-250* oven temp with just a coupl eounces of liquid in the pan. Here's where you can gert a bit more creative with the flavor profile by using liquids which add additional flavor, such as whiskey, brandy or wine, fruit juices etc. The lower pH from the acidity of the liquor or fruit juice won't effect the cooked meat's texture much, not like it would if you were marinating raw meat. You're still using low & slow heat...can't rush a cut of brisket if you want it moist and tender. I've never had a home-cured & smoked pastrami we didn't like (they've all been fantastic eating), some were just a bit better thyan others. I think it's pretty hard to botch one up very badly during or after the smoke, but with the above methods, you should be very happy with the results.
Eric