Since my name was mentioned...
A few years back I suggested moving the list to Google Groups. (At that time, McGill was having some problems with their listserv setup, but it seems fine now.) My interest in Google Groups was that it was modern and probably long-lasting, but many people were (I think) uncomfortable ceding control to a megacorp, so no action was taken.
We have a very large and diverse membership, which inclines me to stick with what we have -- which is, implicitly, acceptable to most (although we have had dozens of departures in the past few weeks). I regret that the flexibility isn't as great as some would wish, but my feeling is it works pretty well.
Thanks for the constructive discussion.
DAn.