Well, I gave in and got it. Funny thing, I already had an EA account (possibly from a previous game I registered) that needed upgrading to Origin.
I've had no trouble downloading or running the game, and no issues with the addons. It does take its sweet time to load (Win 7 x64).
And, to my surprise, the game seems to launch from the executable, without requiring launching the Origin client (my guess is that being a pre-origin game, adding that functionality was too much of a hassle).
Truth be told, if Origin did that, make games independent of their client until online features are needed, they'd win some massive points over steam.
We'll see when my only reason in the foreseeable future to get an Origin game (Mirror's Edge 2) hits.