I was just testiing this last night. For a 100:1 mix, the working life is very short. It's longer with the stronger mixes, and I'm using the full strength dose of sodium carbonate monohydrate. I see a density loss of about 0.12, 30 minutes after mixing. Density drops from 2.92 to 2.80 30 minutes after mixing. I suggest using the developer immediately after mixing. Last week, I was playing using a double strength mix for processing ortho litho, and the tray life was only about two hours. So here are my estimates.
1. 100:1 with 6 grams per liter sodium carbonate monohydrate 30 minutes
2. 100:1 with 3 grams per liter of same (effectively a 1:1 dilution) unknown, but likely a little longer
3. 50:1 with 6 grams per liter sodium carbonate monohydrate (stock) 1 hour
4. 25:1 with 12 grams per liter of same (this is a 2x for paper dev.) 2 hours
#1 was measured objectively and found at about my limit for density shift. #4 was subjectively measured through ortho litho density changes, but not directly a density change. #3 is just an estimate based on 1 and 3. The short working life is not a problem for roll film processing or sheet film on hangers, For tray processing, this would be a problem. As an ortho litho developer, #4 is good, but for prints a little on the weak side. The poor working life may be a problem for me, so I may revert to using e72 for a while. I will also experiment with other accelerators which will likely improve this.