We have the Mark 8000 . You can see it here
Flow Pur: Mark 8000
It uses a box of common table salt for regeneration and that process only takes a few gallons of water.
Price is $240 with free shipping. Mine is about two years old now and works fine. I set it up with quick disconnects so it is easy to hook up.
The problem with the WaterStick is it has a very limited capacity. It is a 1500 grain device while the bigger units like the Mark 8000 and the On The Go sold by Camping World are 8000 grain capacity.
With a water hardness of 25 grains the WaterStick will have to be regenerated after only 60 gallons of water have passed through it. The 8000 grain units will soften 320 gallons before requiring regeneration.
We use about 13 gallons of water per day so the WaterStick would only last us about 4 1/2 days. Under the same conditions our unit will last about 24 1/2 days.