He is telling you BS. The TRS and the T. Rice have some similarities (true twins, same C2BTX camber profile, similar construction for the TRS and the non-HP T. Rice) but are really quite different boards.
The T. Rice is a stiff charger, best suited for big mountain riding (although it will carve nicely on groomers, too). It is also a mid-wide. There is really not much joy in trying to butter with this board or hit the park (other than the jump line).
The TRS in contrast is a softer and much more playful board. It is much better suited for all-mountain riding (some groomers, some pow, some laps in the park).
I went to look at the TRS 157 and Travis Rice Pro HP 157 today. Given that my boots are a size 12, I think I prefer the HP with the SLIGHT extra width. The firm rating is a 6 for the TRS and a 7 for the HP. I dont think that that slight of a difference should be too extreme. I am leaning towards the HP from what I saw and was told however I am open to opinions. I am getting a pretty sick price on the board which is another reason why I want to jump on it.