I have an electric element in my mash tun. It is under a false bottom. It works fine for maintaining mash temps but it is pretty slow to ramp up the temp. It is a 1650 watt Ultra Low density element. I have only brewed with it twice and it works great. I have had other issues that were more related to my being inexperienced at all grain. Measuring the strike water is something to keep in mind since there is a lot of room under the false bottom.
"People who drink light 'beer' don't like the taste of beer; they just like to pee alot."
-Capital Brewery, Middleton, WI