So, for the last several weeks, I've been writing my own mud client to use for Imperian (to be completely precise, I forked an existing open source client, mudpyl, which has been dormant since 2008, and been making extensive modifications to it).
The reasoning for this has been my dissatisfaction with the available options. Mudlet seemed like the most polished of the bunch, but I still felt pretty trapped by their GUI framework for scripting, and also I wanted to use python rather than lua.
It currently supports regex triggers and aliases, macros of almost any keys, triggers on gmcp_events, color HTML logs, gags and text replacement in triggers with Mudlet-like syntax for colors, tab completion of inputs, as well as history of previous commands. Combat modules, which is just a collection of triggers, aliases, gmcp event handlers and macros are simply python modules with very easy to learn syntax hooks. I find it to be just as fast, if not faster, than Mudlet and the coding is much easier (though that's in large part is driven by the fact that I prefer python to lua). It's feature-complete enough to use, I've been using it exclusively for 3-4 weeks now.
Some of the things not yet implemented that I'm planning for the future:
* Easily customizable interface (probably through something like Glade)
* Multi-line triggers
* Ability to run it as mudbot-like proxy for people who want to use their own client like Mudlet as a user front end
* A bunch of useful imperian-specific modules - possibly a healing module that's a bit more sophisticated than gbot.
Below is a screenshot of the interface. If anyone's interested in checking it out or helping me develop it further, please let me know