Something that is not given enough attention is spring pre-load, which is determined by spring length. Pre-load affects the ratio of the Y-crossing value (force needed to start movement) vs bottom-out, which means that for any given bottom-out weight, there can be a variety of force slopes. It would be nice for a manufacturer to be cognizant of this.
I also like what SPRiT is doing with the progressive springs, but their springs lengths are so varied I've had to sort them based on length to have any kind of consistency, which is a painstaking process. The end result, though, is that I have progressive springs sorted by varying amounts of pre-load, which is awesome. The shortest 72g progressives feel much different than the longest in (for example) v2 Zealios. It would be nice to have this level of control without the painstaking / error-prone sorting task. I have no idea how much demand there is for it, though, as I don't think I've heard anyone talking about any of these things before...