This may be off topic slightly, since the original question was whether to use the autosparge in a keg mash tun, but FWIW I thought the autosparge was a great idea, but a little expensive.
I found a 3/8 inch plastic float valve that was temperature tolerant and I built my own. I mash and sparge in a cooler and I went through the lid of the cooler right in the middle. I drilled a hole just large enough for the inlet of the float valve. I used a 3/8 to 1/2 coupler and a 1/2 inch hose barb for the inlet. In the cooler I built a sparge "ring" out of temperature tolerant braided vinyl tubing. It hangs just below the lid
It woked great as long as I turned the flow of the runnings down pretty low. Can it be too slow?? A question I haven't seen. The idea for me was to sparge without having to open the cooler, but unfortunately I still needed to vorlauf.
I've only used it twice as I was batch sparging previously, but I did see an increase in efficiency. It does take longer than batch sparging though and that may be why. I think it must be doing a better job of rinsing the grain bed with the fly sparge.