Well, the priest game being so different I'm not sure it really matters - I mean what sort of advantage can you really derive by being a P/T versus a W/T or a C/T? Does more hours or instant travel really benefit a P/T when food now moves instantly and doesn't have to be carried from place to place?
As far as it being a better combo than W/T or C/T since the drawbacks don't kick in, who cares? I mean, I sincerely doubt you'll see people becoming priests just to avoid the drawbacks of one of the other two combos. "Ha-HA! I'll avoid the troop restrictions of becoming a trader by switching to a main class that can't lead any troops at all! Take that, Game Balance!" See what I mean?
Besides, you've got to have some commitment to being a priest - you give up pretty much half the game when you do. No troops, no battles or wars, no looting, no civil or police work. Virtually no H/P gain for the class means you may actually not even have enough H/P to gain some positions (I have seen this happen to a couple priests). You get a lot in return, but I don't think that a P/T combo creates a ridiculous combo the way that, say, P/I would.