Thankfully, I haven't had any big issues w/ Phil's Sparger.
It can stop spinning when my hot liquor tank is nearly empty, but I don't see that as an issue. I generally don't have a problem hitting/holding my mash temp either.
I also adjust the height above the grains as much as I can - so the water doens't have to fall too far before making contact. Also, my setup means the water doesn't travel very far between leaving the hot liquor tank and exiting the sparger. I'm quite certain I'm not losing anything close to 20 degrees.
I guess I'll keep using it until I find something better or it breaks...