I have developed a alternative NAS solution for Omnia ( 2GB version ). Where you install a 2.5" drive right inside the original box. I have tested it a bit and it works well for me so far. I am not sure if we will get any problems with heat. But if we do there are several ways we would work around it.
Right now it contains of the tray, and a converter card that transforms the port from mSATA to SATA. The things we need to do now is to order a good cable for the drive and possibly update the converter card so that it fits better.
I am posting this topic here to see how many people would be interested in such an upgrade. I think that the complete kit price ( without the HDD ) would be about 20€. And we can prob send it out with regular mail.