I do it from time to time... as I've written before in a thread here to a similar topic, I also do it "feet over my head" style... for very much the same reasons as others have mentioned - I completely lose interest after I cum, and it simply tastes great when warm...
Though I have one particular problem with the said position... as my balls "tighten", so to speak, as I'm about to cum, they also pull up really high towards my belly and inside my body, which creates a very uncomfortable feeling... it's not painful, but really uncomfortable... I don't know if any of you guys ever felt it?
And when I get back on my feet again, it takes a bit of time for my balls to get down to their "natural" place...
Other than that... I like the feeling, the taste... of course, I discovered it by accident a few years back when it was no problem at all to hit my face cumming while lying on my back... nowadays... my orgasms are not so powerful...