Intellectually, I totally get your line of reasoning Sean, and I'm sure most users do the same thing you do. But my gut reaction to this practice is a puzzled, "why bother with R/W"? I suppose to some extent it depends on your interest in shows that aren't "keepers". As barren as the TV landscape is these days, in any given week I'm stockpiling a dozen or more series: some old nostalgia reruns, some new and current. In every case this is stuff I more-or-less will keep long term, so when I clear it off the HDD at 3 or 5 episodes per disc, I use TY DVD-R media. If its a series that gives me momentary entertainment that I'll never want to see again, I just timeshift it on the HDD and it never gets offloaded. Every now and then I bump up against the 80GB capacity of my HDD, because I also record a ton of movies from TCM, but generally its manageable.
R/W media is more expensive, and I don't use the eraseable feature often enough to justify it. (There have also been a lot more complaints on AVS about R/W glitches than ordinary -R.) The only times I've really
needed R/W was to make VR backups of titles I knew I'd want to return to the HDD later for re-editing, but once I realized the Pios would let me format a cheap -R disc as VR, I stopped buying R/W. Besides being cheaper, the virtue of -R is you can pass the discs to anyone and they'll be able to play them: there are one or two series on F/X or HBO that I watch on archived -R then hand off to friends/relatives who pass them around in ever widening circles.
It probably pays to take a look at our viewing/archiving habits after a year of owning a DVD/HDD recorder, and consider whether a change in media usage would be beneficial. Offloading to R/W is the easiest solution to HDD overload, but you lose a big advantage of the HDD: not wasting burner hours for watch-and-erase timeshift recordings. Especially now that new DVD/HDD machines are no longer available, anything I can do to prolong burner life, I do religiously. If I'm gonna use up precious laser life, it's gonna be on -R that I keep in my library or pass around for others to enjoy: R/W is a luxury I'm not willing to risk anymore.
Of course, personal background also affects my opinions on media: I'm one of those nuts who have thousands of VHS and Beta tapes, enough to build a guest house out of (if I had any land to build on). Coming from the tape era, I'm still floored by the ability to store two entire seasons of a show in the space taken up by a single VHS that holds at best four episodes. The freedom to keep entire seasons at no cost in storage space still makes my eyes glaze over

. If I live long enough to see SD cards with 6-hour hi-def capacity become dominant, I might have to be medicated to keep me away from the recorder.