Apart from the sheer joy of building and successfully using a homeboni, do I give up anything by just using the drum dump method like this guy?:

http://www.youtube.com/watch?v=SZ0kAHv3 ... re=related

For our small rink I figure I'll need less than 50 gallons to get a 1/8" layer (per the calculator on the site here). Seems like a no brainer to me to get a trashcan, fill it with hot water and let 'er rip after a good shoveling and scraping.

Clearly the feasibility of this approach diminishes to near zero as your rink grows in size...but with a small setup, it seems pretty sensible.

Am I missing anything?

Bucket dumps are certainly a viable approach to resurfacing, though I've honestly never filled up a bucket with hot water and let it all rip at the same time. More often, when I'm strapped for time or just don't want to wrestle with the homeboni, I'll just let the water come out of the hose without a nozzle on it. Since it'll be cold out, the hose will be stiff and easily moved, and you can let it run wherever it needs to go.