Stu, in theory that's a great idea, but there's a problem or two. First and foremost, most systems are not completely emptied when drained, mainly because the hoses go uphill, downhill, around bends, through fittings, etc... Consequently, there's always a bit of water left in the system, water that will surely freeze, expand and bust something.
Next, the water is heated by the engine, passing through a cast iron manifold, which will rust like crazy if it's not protected by the rust inhibitor in the antifreeze--not a good thing.
Most of the pink, marine antifreeze solutions are non-toxic, but they have little in the way of bacterial inhibitors. Therefore, I usually add a cup of Clorox bleach to the winterized tank along with the antifreeze--something to kill the bugs. I do not, however, add the bleach until after the antifreeze solution has been thoroughly been flushed through the system. The bleach is then added to the tank only. Bleach can do some nasty things to metals as well.
When spring arrives, I pump the entire system dry, then fill the 70-gallon tank with cold, fresh water, and flush the entire system again, running the pump until the tank is empty. Then I refill it one more time, this time, though, adding a cup to bleach to the 70-gallons of water. This keeps the bug count down, but it's not strong enough to hurt the engine parts or electric water heater.