<snip> I guess if the cost for TS/RDS or Citrix is too much for the client we can look at the VPN and using SQL Server and see if that will be fast enough for them.

Just verify who is going to pickup the costs involved with the extra support. Remember you are saying that this topology is OK, and if there are problems you will be in the crosshairs.

With your comment about the costs, in this case if the client can't afford the costs to do the remote comms properly they can't afford remote access, you do not need the hassles.