I have had a similar problem:
I had my five toons in UC and wanted to move them to SM. Every time i follow my main guy with the other four I whould get really high ping times from the server and ultimately get disconnected. I thought it was a problem of my server (EU patching was yesterday) so i created 5 little gnomes on another server (cute, aren' they?) and ran them to IF without a problem.
Kind of scares me to hear that someone has similar problems... let's see if it works tonight...
Bunny (Durotan EU)