I was working from some US Mustang tunes and they followed the ID data although not exactly. I don't have access to Australian ID1300 tunes but trust what you are implying. At least with these injectors you can dial in the low slope pretty quickly.
Here is an interesting one, two cars with Siemens Deka 60s, great fuel trims and AFR matching commanded.
With Ford Motorsport Offset:
Low Slope of ~61lb/hr, High Slope of ~65lb/hr
With Ford XR6 standard Offset:
Low Slope ~110, High Slope ~70lb/hr
Car 1 had slightly superior fuel control. As I have learnt, Offset plays a big part in this.
I have also found that the values can be calculated with info logged with SCT and a good AFR gauge located pre cat. When you do the maths on injector pulse width you start to see how this works.
My LPG injectors are a bit like the values in the US ID1300s with a low slope of just under 59, high of 62 and a breakpoint of about 4ms (using the SCT logged data). When I put them on my mechanics flow bench they came out very close to these values. When they are this close you can get away with quite a few values. Will be interesting to see what happens when I remove the other restriction on Thursday.