I do think its more than 5%, but from what you described I don't think you're in that X%.
So...from a high level it sounds like what you want to do is spin up N workers, send them a UUT to work on, and then have the results recorded to disk. To be honest, I'm not sure why you need DVRs or any data sharing at all. Could you clarify?
->To me you'd have a QMH of some kind dealing out the work to your N workers (also qmhs) and then a QMH for logging which collects results from any of the N workers. You could do that with manually written QMHs, an API like AMC, a package like DQMH, or actor framework. Separating out worker functionality from logger functionality means (a) for those long running tests you could write intermediate results to a file without worrying about interfering with the test and (b) you can really really really easily switch it out for a database once you've decided you need to.
As a side thought, it sounds like you are re-writing significant parts of teststand (parallel test sequencing, automatic database logging and report gen, etc.). The DQMH library mentioned above seems to be written to work pretty well with teststand (nice presentation at NI week and I believe its also posted on their community page). Just a thought.
If I'm mistaken, or you can't use teststand for whatever reason the tools network does have a free sequencer which I think is pretty cool (although I do RT most of the time and never have a good chance to use this guy): http://sine.ni.com/nips/cds/view/p/lang/en/nid/212277. It looks like it could be a good fit for your workers.