Dirty'
We use it as a tool here all the time. Its for when you want a pilot to not start to slow the climb at all and keep it going up so that you can get above someone that is either climbing behind them or even that is in front of them, and then go on to other trafffic. The reevaluate later to see how it is all coming out. If his expedite isn't anything different, then you cap the climb and go from there. It is more of a try to get the pilot to his/her requested altitude for traffic that you see either coming up or for something that isn't working the way that you would like, but you don't have to take immediate action with. Also no brain power to start figuring out rates of climb and time to closure etc...
regards
Scott