a lot of people told me the drum brakes would be a disaster, but I haven't found that to be the case and I weighed 300# when I bought the bike so I really tax them. they work at least as well as rim brakes in dry conditions, and in the rain there's no comparison. I also like the fact that I can ride them down the hill without worrying much about overheating etc (they are also called "roller" brakes I think for this reason.)
that said, I haven't had a bike with disc brakes. and there is a new "DLX" version of the Soho this year that has a disc brake on the front wheel (though still a drum brake on the rear). I can only assume they did that in response to requests for more stopping power, but I"m not sure.
for what it's worth, I haven't touched either of the drum brakes in 1300 miles of commuting. for $500 I think it would be hard to beat that Torker unless you can find a 2009 Giant TranSend EX - I saw one for $650 or so and it has an 8-speed IGH with disc brakes. I really wanted the belt drive though so I paid the extra $70 for the Soho.
good luck