Got a chance to work with some Linksys SPA941 phones and sipX.
These phones were connected to an Asterisk system originally and we were moving the customer over to sipX due to a system failure.
Ran into a few problems with the phones... First thing I did was a factory reset on the phones (needed to be done right on each phone in the setup menu).
I upgraded each of the phones individually with the most current firmware. I could not find good information as to how to automate it so i used the manual method (http://ip.of.phone/upgrade?tftp://ip.of.sipx.pbx/spa.bin). I did use the sipX device file manager to load the .bin file to the pbx.
The next challenge was getting the phone to pickup the config generated by sipXconfig. Finally figured out to go to the Admin / Advanced / Provisioning page on each phone and change the profile rule to read '/spa$MA.cfg'.
Still having issues with call pickup from park orbit and attended transfer of calls.
I created a new wiki page documenting what I had found: Linksys sipX Configuration