Okay, just worked my way all the way through this very useful thread. Our contribution:
Harbor Freight Multi-Function Tool. We're getting to the end (thank the Gods) of a complete deck replacement, and use this tool fairly continuously, every day. We got two, eventually, and got the $5 extended warranty with each. With two we can both work at the same time, keep them set up with different blades, or with blades set up at different angles. Also if one croaks, you still have the other. They work great (though loud, I use ear plugs) and are about a tenth of the cost of the Fein Multi-Tool.
i totally agree on the multi tool, absolutely indispensable. i thought it paid for itself the first time i used it. also the finger sanding attachment can get to places you would not believe, dramatically reduces sanding time.