I use a ratcheting tie down to compress my suspension to the same distance 'tween the axle and fender as when I'm sittin' on it. Then 'guesstimate' the measurement and RIDE! 51 k on this one, I like the belts. Never even heard of the E kit, I'll have to look at it.
I've got the gauge Harley sells to adjust the belt. Used it once. I couldn't find it now if I wanted. Kind of a joke if you ask me. It was a gift from someone. I just grab hold of it and see how tight it is. If it feels about right I don't worry about it. The only people I know that have had problems are the ones where the belt isn't running true.
I've got the emergency belt but never used it. It cost around a hundred bucks if I remember right. It's one of those better to have and not need than the other way around.
I wasn't really crazy about the belts when they first came out but so far no problems. With a chain you can all ways fix it out on the road. With the belt you have to pull the swing arm and all the other stuff to get the new one on. A real pain in the azz.