Krdc is a remote connection application available for Linux but mainly for kde based DE. It has defaults for RDP and VNC but I think it could be extended further.
Integration of konsole
Make it a nice big box where you can switch between konsole tabs and rdp sessions, manage it all from one place.
Split windows
multiple session in cases where I have 4 rdp connections open
But im not actually doing anything on them other than watching an output or moving something around. Having a split window would greatly improve productivity.
book mark tree
Book marks are folder based from the top menu.
Alternativly you have the history view window to the side
While this is fine for small set ups it quickly becomes annoying when you want to connect to another box quickly
The connections are shown with the username domain and ip
doesn't work with ipv6, this is a bit of a non point as almost all connections will be ipv4
Log location and debug steps
Where are the logs.
Who knows
you can do a little error checking by running from konsole that will output a bit
or you can use kdebug and just select krdc
Change between freerdp and rdesktop
This should be standard as some clients have trouble with one or the other. Adding the connection options such as security model should also be included.