I thought I'd report back after a few months of running 1.22.
I ran it a while without too many issues, but still just enough gremlins when using OCS or LiveMeeting for conference calls, lag on Xbox, and other little things here and there. I got fed up with it, and decided to buy a $15 Gig-E switch and hook it up to my old MN-700. While the MN-700 doesn't have the rich features and speed that the DIR-655 has (and very noticable when downloading huge Blizzard updates, streaming Netflix movies, etc.), in the end, it's more stable, and less laggy.
For a while I have had the DIR-655 plugged in behind the MN-700. The machine behind the DIR-655 has a definitely less reliable network, but in general, my DIR-655 reboots are non-existent. But it makes sense, because the router is no longer doing much actual routing -- it is barely better than a dumb access point now.
I'm sorry, I'd rather have a slow connection with low latency than a high bandwidth connection that is unreliable and latent. The DIR-655 is going on Craigslist.