Hi,
please check my previous work, feedback and strongly consider my bid. I have a deep knowledge and experience in the field.
Backing up a drivers ( just to clarify, you need just \SystemRoot\System32\drivers folder, don't you? ) to mountable VHD and doing an incremental backup doesn't seem to be complicated task and I can easily handle this job. Even without open-source source.
Unfortunately I didn't develop for VMware and Hyper-V before, so I can't make a strong offer there, but I can do a small research if you have time, of course. I have a friend developing that kind of software so he can give me some advice.
Please let me know.
Regards,
Dmitry