It does indeed work without any errors now.
Don't follow Treo instructions to install the app and do not do the copying of files mentioned in the text file.
If you look closely at the text file, the copying of files is only for older AKU's (I believe that's the right term).
Just install the PalmSMS CAB file and reset the device when it ask you too...let it boot back up and enjoy the treaded SMS.
I have tested with multiple messages outgoing and incoming and it's worked perfect for me so far.
Also, text size seems to be the same in either landscape or portrait so that bug I read about doesn't seem to exist on the 6800.