depends somewhat on your water useage. if it is high and very hard water I'd go with one of the larger RV type softeners.
If water useage isn't real high the larger "waterstick" softener is an option. it is much smaller (hence softens less water) and less expensive. That is what we and my brother have. Works fine for us, but again if use is high and water hard a larger system is probably in order.
The waterstick is good for 150 gallons at 10 grains (pretty hard water), 3 grains roughly 600 gallons, 15 grains (very hard water) 100 gallons.
The larger more traditional design softeners sold in RV stores are double or triple the capacity.
In any event, it's worth it. less scum, less buildup, easier to wash and clean. If the water is very hard it won't eliminate ALL the scum and scale.
Both use resin beads and salt as water softeners do, the waterstick is easy and quick to do a regen on.
you will find that most of the smaller systems including the waterstick regenerate with table salt rather than the large pellets used in home systems. Which makes it easy to regen on the go.
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!