I wanted to update this b/c I've discovered a few other things as I've continued to work w/ my tank of this developer. Again, just my experiences, so take w/ a bunch of salt.
First, I'm still fiddling, but I think the replenishment rate from syrup may be more like 1+14. I think I began at something like 1+17, but I've been leaning towards rounding it up. Say I run 18 rolls, I'll just replenish for 20. With a 3.5 gallon tank the size makes drifts slow - which is great b/c it makes any small errors less dramatic, but it also makes nailing the exact numbers down hard to do, since the difference btwn something like 1+17 and 1+14 is scant. I think working w/ a small batch would be easier to pin down a number on.
Also, b/c I when I dump half the tank off every few hundred rolls or every few weeks, it heats back up, by say a half or 3/4 of a stop. Makes sense since it's sort of like un-seasoning half the tank. So it further makes it hard there to nail a number down, since working w/ the tank takes on a sort of rhythm of it's own. Again, a small tank of developer would be much easier to get a read on I think.
Has anyone else given it a go? Numbers?
Finally, this was a big one that just reared it's head, I think it came w/ the hot weather. Streaking, or drag. I let the tank sit for just over two weeks (w/ a saran wrap floating lid), and I noticed streaking popping up on the first few batches of film I ran when I came back. Big old drag line that will pop up in areas of, say, zone iii densities on 120 or bigger (no prob w/ 35mm). But after I run maybe 20 or so rolls, it doesn't show up on anything after that, at all. I didn't see this at all in the winter or spring, and I'd let it sit for 2 or 3 weeks a few times, but it got hot here so the temp in my room is about 85 degrees now. My guess is that it's the developer is oxidizing much faster in the heat and it's causing this.
My solution for now, since I can't get rid of the heat, is to pick up a few hundred sheets of 8x10 xray film (like a quarter a sheet), and if I have to let the developer sit, then I'll just run 25 or so of them through it before I start at it. At least while summer is here. It's an added expense, but I still think it's worth it. If it works...
So it's become very much a feel thing for me now...but I LIKE working that way. The replenishment part is really very easy I think, if you can stand the occasional 1/2 stop drift up or down and are willing to learn your tank. But stuff like the streaking/drag is a different story: a problem that has to be solved. But other than that, it continues to be a lot of fun to work w/. And the film looks really really tight.