Just moments ago I was giving the Penn Plax Super Battery Vac a try. It's pretty much just a cheaply-made toy. Not much suction--it could not lift my medium-sized gravel at the bottom of my 25 gal
tank with two brand new batteries. The instructions said to hold it just above the gravel, but to have any effect at all I had to burrow it into the gravel surface. The most distressing thing was that it had a pronounced tendency to disassemble itself with use--the power head would come off the tube, resulting in water being sprayed everywhere, etc. A very frustrating disappointment.
Like you I was wanting a method to vacuum gravel without pretty much emptying my tank with the siphon. Never mind that I have difficulty controlling the siphon itself with just my two hands, and don't need the additional complication of maneuvering it around trying to clean gravel at the same time.
The Python seems like overkill to me, but....