I thought about the whole auto sparge idea....if you drill a hole in your mash tun .....then lets say you want to brew a 10 gallon batch instead of 5 gallon....the auto sparge won't be in the right place for the larger/smaller grain bill.
I thought the autosparge was a great idea, but a little expensive. So, I tried what you found a little while ago. i don't know if it's the same valve, but it looks about the same as I remember (i'm at work)
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. Another question, can you have too much water in a fly sparge as long as you stop at the correct SG or boil volume? Basically, does it matter if there is a lot of water above the grain bed and ultimately left behind in your MLT after you reach your SG or boil vloume?
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.