Thats certainly a fine method so long as you do not have too many capping/hives. I have drained them for ages, then into a solar extractor when I had more than six hives worth to deal with.If you put them in a rapid feeder with the central section removed all you need to do is put the sealed feeder over the crown board hole. Job done!
Open the feeder once a day and give the cappings a quick stir and within a week the cappings are like dry sawdust. The stirring prevents the build up of comb as well.