As with many others, I've spent a fair chunk of time trying to configure Symform with my TS412. An excellent idea to be sure, but it just doesn't seem to work well with the QNap NAS. Very resource (CPU) hungry and uploads are painfully slow even with a 30 MBit up and down fibre-op connection.
Sad thing is, on a Windows 7 PC with a small HD, where I don't have the extra space, after the initial sync, everything seemed to work well. So ... I got the wise idea to use the one account, using the NAS for the contribution and sync the files from the PC's in our house. NAS CPU still maxed out and one of the Windows 7 PC's is under significant load as well.
As many have said ... Symform is a real good idea. Too bad it doesn't work! I'm afraid I'm going to have to bury Symform.