I'll switch to RTCOMM when:

1) it actually makes me invisible when I set my status to invisible - I know that not all chat service let you do that, but RTCOMM should work properly with those ones that do support it.
2) I can tell it to not auto-IDLE nor auto-AWAY me. It should keep the status I told it, no matter how idle I am, no matter if my screen dims, etc.
2a) it'd be nice if RTCOMM had some visibility into, and integration with, the power management stuff. Don't power down if you're signed in. Don't fully shut off the screen if you're not AWAY (partially dim the screen: yes, fully blank the screen: no). Settings/options like that.
3) easy to create custom statii (like pidgin) -- I like to have more status info than just "away". Like "I'm in a meeting", "I'm watching TV", etc.
4) I can have chat logs that automatically get stored on the data device of my choice (removable card, internal card, somewhere under /home/user).

If those are do-able now, then great. Let me know, and I'll switch. But, from what I've heard whenever I've looked into switching, these are ways in which RTCOMM is not yet fully baked.