Based on what I've read and the videos I've seen, "envirosafe" if it really is, is only a bonus. As for most dealers/shops I've been to, their shelves are already filled with dust covered ammo they can't sell. Yes, $1+ per round of 9 is high for range ammo. I don't mind spending money on good quality SD ammo. The Speer Gold Dot I have now is $1.30 a round.
I've loaded the Sinterfire frangibles in several calibers. It is a hoot to shoot steel close up, but I don't know how well the sintered bullets would work in defensive situations. I don't think they were designed to provide cavitating and explosive wound channels, but they do eliminate the lead problem from conventional lead core bullets. Of course, now you just get copper and zinc contamination...
I do know that in .308 Winchester applications, the 125g SF bullet prints where the 168g SMKs print.
I’ve seen ballistic testing videos of the NovX and it’s pretty impressive. Unlike a hollow point sending several pieces in many direction. The fluting of the NovX causes a much bigger wound chanel. Other benefits are lighter weight, higher volocity and less recoil. I’m sold on the pros alone. I just want to try them to see if they perform as advertised.