I've been working with xMff to get asterisk working with a Luci front end. I use my Asterisk at home on my Asus WL500GP - both my wife and I work from home.
I've been able to cut the modules loaded right down - and have also broken up asterisk into many modules (about 80 iirc).
The modularised version and the UCI configuration generator is a WIP and is in the Luci Devel SVN (under asterisk-xip). The LUCI front end is very much a WIP.
I am running Asterisk 1.4 with voicemail, MeetMe and some other stuff.
I only use ONE encoding (ulaw) to avoid any transcoding (apart from sound files in gsm)
I haven't stretched the system to breaking or anything, but I have been able to get
2 External Calls + 1 Internal on a MeetME Conference call at the same time as answering another incoming call.
The audio is fine 95% of the time. You get the odd glitch and outage - but it's hard to know what the cause is.
I use my ISP as my provider... which probably is a good thing .. means the servers are only a hop or 2 away from my ADSL2+ connection.
I can transfer calls from my phone - but have no forwarding setup. I've transferred external calls to another external number without glitch.
hope this helps