I'm a reluctant soft water fan for RV'ers. I have seen, and grew up with water softening when I was a kid and though expensive, and a hassle, it helped with things like laundry, prevention of hard water deposits, and better drinking water, but really, it was hard to notice a difference when it needed recharging.
Now, as a full time RV'er, I'd only consider the systems I've seen if I tended to plant myself in a couple areas of my travel circuit where the water was noticeably hard. And you'll find those places in your travels, your neighbors will tell you right off.
Also, if I were to get one, I think I'd do it at the Quartzsite rendezvous where you find experts and usually reasonable prices.
What I'm saying is that if you have a home base with hard water where you stay in your RV a lot, sure, get one. If not, wait a bit and travel a while before deciding. The systems are fairly expensive.