I agree with David, the ability to copy and modify into a personal database will be useful. Regarding the quantities calculator, I think this is brilliant. I have one small issue with it though. On several of the two-part formulations I checked, Pyrocat HD, Rolo Pyro, and Kodak D-85b (in Lith/Ortho), the quantity input is used as the total of A+B rather than the total of the two components separately.
I know when I want to make a two-parter, I want the quantities specified for the total of each solution - not the total when mixed. It can make for some odd numbers... e.g. Rollo Pyro: Quantity set to 1000ml, part A start with 266.67 ml of water topping up total volume to 333.33 ml after adding chems, Part B starts with 633.33 ml before mixing in the Sodium Metaborate, for a total of 1000 ml at the end.
Perhaps the app's programmer could make either a modification to allow either setting whether we want an A+B total volume (as it currently stands) or an A, B volume (each, not mixed) as two part formulas are usually presented.