For $8 for the Camco you can certainly afford to be disappointed.
I changed our shower head to the Oxygenics Body Spa RV eight years ago ($26) and we have been quite satisfied. The design accelerates the water speed giving a sensation closer to an at-home shower without increasing the water consumption rate. It does have an on/off feature which is activated by turning the knurled end of the handle adjacent to the hose connection.
The lime/calcification/debris issue is a function of your water and will affect both the shower heads and sink faucets. You may benefit from using a water filter for both city water connections and tank fills.
"Good judgement comes from experience. Experience comes from bad judgement."
Air #48582, S/SO #003, WBCCI #4584