big d,
I wouldn't worry too much about the mash out and the temp of the grain bed when sparging.
I used to worry about it but after many discussions with lots of other brewers, no-one really gets the grain bed to the sparge water temp.
The only way to really get it there is if you have a method of direct heat on the MLT.
Lately I've switched to batch sparging though and that tends to get the temp closer to the sparge water, but that wasn't why I've started batch sparging.
RDWHAHB
Doc