Re: QNAP server using Subversion Setup Questions
Sounds to me like you're on the right track. I would look at Synology also. I've been really been impressed with their software. Their products are probably similar to the QNAP you've been looking at. They're a little more expensive but very solid in my experience.
You might want to look into a web-based document management system and just use the NAS as backend storage. VPN connections are always buggy and trying to get them working out in the field is a huge pain.
If it were me, I'd set up web based document management secured with an SSL certificate, and use the NAS as backend storage. Then I'd replicate this NAS either to a cloud backup service, or to another NAS located offsite. If you're concerned about privacy, I believe there are ways to encrypt a cloud backup before it's transported for storage.
At work we use a document management system called WebDocs. It's not very good, honestly. But, something along those lines might be what you're looking for. Maybe subversion will work for your needs, hard to say.