I don't realy notice any more drain then normal, I have a Samsung Intrepid, I have Goosync, and GPStoday running all the time and I can go two days before charging, when I had my Touch I also used Goosync and never realy noticed less battery life, but now that I think about it I did have the large extended battery so maybe I'm not realy the guy to ask
I have it set up to sync every half hour, but it realy only takes a few seconds to sync calendars and contacts, I have about 200 contacts give or take, you can set it up to only sync durring certian hours, and on certian days so it doesn't run all the time.
I hope this helps.
Terry