We have clients in the far north where internet speeds between communities and with the south are very slow (we're talking modem-slow). They've been getting by with TS although they used to use Citrix which had much better performance (their IT dept could no longer support it however). We've had to adjust our interface to be very simple to aid the speed of transmission and we've had to remove all radio buttons and checkboxes as they don't trigger a refresh of parts of the screen and result in long delays. They have the usual printing problems; they are able to sometimes save as PDF and move the file to a location they can copy it to their local machine. I don't think clipboard contents are a problem but sending emails won't launch Outlook on their local machine so that's a problem. Would any of your technologies solve all of those problems? How about a Mac client?
We have considered leaving Cirtix. There server setup is far more complex than anyone else, not to mention the cost. The XenApp product is the only one we still use. It sounds like you have been using 'traditional' Terminal Services; however, in Server 2008 RS the RemoteApp streaming seems to run faster and is less confusing to the client.
The Ericom software is supposed to accellerate the traffic for RDP, and 2X is a Citrix alternative which is also faster than 'normal' Terminal Services. We have been able to get all of these services to run on a Mac, but RemoteApp is a bit tricky on the Mac, so we nomrally just send our clients shortcuts so thaey don't have to enter a bunch of stuff. 2X seems to work best for mapping scanners and other devices.
I would be interested in doing some test with you. If we test with out 'real' clients, they get mad and cancel their subscriptions were with you; we all realize that this is being done in the name of testing and there is no comitment implied from either party. By performing these test publically; hopefully we can get additional feedback and publish 'FileMaker-specific' testing results; something that these other sites are missing.
We use a terminal server (2003), and optimised the layouts to prevent refreshes. We have found the flexibility with being able to print direct on the remote computer, and access the remote computers HD as a local printer/HD on the remote desktop connection app works well. It's light enough on network resources to run on a .5MBps connection, though printing that way does take some time.
And it's Mac/Win compatible.
I have't tried any other of those remote clients you mention, just adding my thoughts.
Am looking for a Cloud solution. Happy to test some stuff if that can help.
We now are support 7 different 'non-traditional' FileMaker deployment methods, including a new HTML 5 which allow a full FileMaker 11/12 experaince with no downloads required. If you would like a trial account to play with, please let me know...