At a $120,000 price tag you're not looking at the potentially 250,000 patients at MDR2, you're looking at a subset of the 28,000 patients at MDR3. At $120,000 Insurance companies will say "you're not at MDR3 yet so we won't cover it.".

So is it better to have potentially 10x the patients at 1/3rd the price?

With the broader usage you'll also get more media attention and word of mouth.