ABG is nice, I wish everyone had that.
Your web site lists the DS flange spacing at 19mm. Seems like that's a typo?
I agree that center of the flange is the norm. In any case the measuring method should be listed on the web page (or provide a link to the diagram) so as to not mislead customers. I'd be unhappy if I bought a hub that I thought had a superior 19mm or pretty good 18.1mm DS flange spacing only to find it was really 16.5mm.
The correct drawing has already been posted.
The specs listed on our website are those provided by the manufacturer and in the seven years I've been working with these hubs have yielded correct spoke lengths when used in any calculations.
In terms of an actual technical drawing (as in one you could use to produce a hub vs a simlplified drawing posted on a website) all dimensions are given including flange widths. You need to do a quick bit of math to get the build dimensions you need.
With regards to RCF dimensions, those are pretty much fixed by the component makers. There is a min clearance between the lock ring and the drop out required (for instance it is 1.1mm for Shimano road), there is the height of the cassette (freehub body length) and then there is a specified min clearance between the last cog on the cassette and the hub flange (for spoke clearance). No hub maker can compress these any more as there will be chain line issues and possible problems with chains hitting dropouts or spokes. 18mm is pretty much standard at this point for 10/11 speed hubs unless we move to 135 OLD (or use wafer thin flanges and squeeze out another fraction of a mm).
These are all laid out in the factory technical manuals for Shimano, SRAM and Campagnolo.
What can be worked on is the non-drive side of the hub. The whole goal here is to achieve as much stability as possible and to balance spoke tension as close as possible. This can be done a few ways.
Most people thnk that you just need to shove the left flange as far out as possible to do this but this is a gross oversimplification. What can happen (and I have personally seen this with other Taiwan hubs that are all the rage at the moment) is that the flanges get place directly over the bearings and when spoke tension is added it can stretch the bearing bore. This means that the NDS bearing can become unstable and lateral play can develop. This is especially true if the hub shell is made of cheaper alloys to save a buck.
Another way to balance tension is to decrease the NDS flange dia. That may seem counter-intuitive as it seems like you are decreasing the base of the triangle but it has been demonstrated to me by the engineers at Novatec to increase NDS spoke tension.
Another method is to go 2:1. This can work but makes truing a bit more difficult and spreads the same load over fewer spokes. If the rim is not drilled specific to the hub this can shorten spoke life. This is fine for a wheel with all the components designed from scratch to work together but not so much for custom building wheels from off the shelf parts.
My point being that the builds we are offering with the kits have been the exact builds I, and my team mates, have been using for our training wheels for several years without issue.
If these are stable enough to stand up to my heavy olde arse and a ton of 1500w efforts over the years I'm confident that they will be stable enough for anyone else who wants who use them as well. Every part offered in these kits is a mature product that has seen wide distribution for several years and has proven to be reliable.