Persistent VPN in conjunction with RMS

I'm guessing you'll have higher latency unless your VPN is done from router to router (with plenty of memory) if done a the NIC it will slow it down even more.

What kind of lines do you have between each store and the HQ? Its the bandwidth in this case that is as important as the latency. You can test this by pinging each site from the HQ. If you don't know how to use PING.exe let me know.

The results of the ping test will give you the round trip latency in milliseconds (ms). Find out what the tolerances are from Microsoft or your provider for the connection