I always take a second guess on what most reps say. They generally are trying to push a product, they are trying to sell it still. In this case, however, I have to agree with Rory. If the housing structure and drivers are the same, the sound will be the same assuming tips don't change (tips can change the sound of an IEM). The only sound differences that will occur is due to driver variation among other factors (tips, bore, etc.). However, in this case, the pinhole bore is much more sensitive than what a tip change can offer.
I still remember when Westone reps stated that the W40 and W4(R) were different and sounded different due to different acoustics. Measurements showed the exact opposite.