OK, glad to hear that there is progress on this as not having DWG access is pretty limiting these days, as I'm sure you are aware.
However the Open Design Alliance libraries are not freely redistributable, (unless the licencing has changed recently), nor are the libraries themselves available for download for individuals. As a Linux user I can read the spec or download a windows utility. This doesn't help write free software CAD applications at all.
If QCAD uses these libraries then it will cease to be freely redistributable in Debian, as it would then depend on non-free software. Now you have a business to run and having taken out an ODA licence I guess using those libraries makes sense for you. I assume they are rather more mature than libreDWG is?
However for the free version it would be much better to use the libreDWG libraries even if they aren't quite as good yet, as then QCAD remains free software that can be built and run on all architectures, and distributed by Debian and its derivatives.
I don't know if it is easy to keep this option of using the alternative library open or if that introduces complexity to the codebase that you don't wish to support? Hopefully the API of the two libraries is not too dissimilar. Having no access to the ODA libs I have no way of knowing.
Have you looked into libreDWG yet? I have found the responsiveness of the authors to be remarkable and they are eager to have test cases that don't yet work right. http://www.gnu.org/software/libredwg/
I'm sure they would be extremely grateful for any insight/feedback you could provide as someone with great experience in this area, and being pretty much the exact person they are hoping is their userbase :-)