Thanks "nobody", I think I must have been looking at the wrong spec sheet! If I went for the 2930 (with external adsl modem) would my thinking for a SSL tunnel work?

Yes, SSL tunnel will work (works for me) with the 2930 + Modem on several locations.

I still havent understand your setup:
"Thinking of upgrading to a 2830 at main site to service incoming remote workers. At present this is configured via a 2820 which allows VPN passthough as the router sits externally to the network on a 2nd NIC which is the external side of Microsoft's ISA firewall. I like this feeling of security although I know many will say that the Draytek will provide this!"

The 2820 is behind another router which is configured so that PPtP goes through it to the 2820 ?
Also, I have not tried the OtP features yet.

But, if PPtP to the 2820 is fine, then, SSL should work also.

A note regarding SSL VPN:
What I mean here is the VPN using the Draytek Smart VPN client, not the VPN tunnel which is established using a Active-X or Java Applet.
The Active-X/Java SSL VPN works not reliable for me, because most times the Java configuration/version of the client is not compatible with the routers expectations.