Yeah, I'm going to pick some up at Advance Auto Parts this evening and put them in. They're expensive, but only relative to standard plugs, which are insanely cheap. My main hesitation on dealing with the plugs has been that there's quite a bit of rust in the right rear socket. It was that way when I got the bike. The other three are clean, but I've been applying the "if it ain't broke" principle on that rust-filled one.
I know what I need to do, though: PB Blaster, let it sit, and then carefully remove the plug. Hopefully I can sop out a decent amount of grime from the socket, and then put all four new iridium plugs in.
Still, I'm curious if anybody has any thoughts on the sound my bike was making as I was trying to start it. But it sounds like, regardless, I'll see some benefit from the iridium plugs (though I haven't investigated the plugs that my bike currently has, so I guess I should check that out first).