| Hot water from the kitchen or laundry tap is fine, and they do float at first (like ice cubes do!) but will sink as they thaw (this is how I know they are nearly ready). I just give them a stir a couple of times to rearrange them, and once they are soft leave them for another 5-10 mins to really warm through, and then feed... never had a problem.
I didn't mean to sound as though I was putting your idea (the defrostinator) down though - there are circumstances where it could indeed be useful...
Jamie. | 
