The skinny tyre vs braking power thing is a bit counter intuitive, but whilst you get less contact patch, there's a lot of pressure on it as a result of it's size, and it's also pretty constant compared to knobblies. The only time I've ever had problems with axle movement under disc braking was with 160mm rotor Hope mini's on the prototype forks which had a brake mount in the conventional place. It's not necessarily the ultimate power, but the relentless consistency you can apply on road slicks that means discs are fine. This prompted the move to the 'wrong way around' disc mount BTW.
Personally, I go for discs every time, and it's not actually an ultimate power thing. I'm pretty sure most V's are less powerful than my teeny disc Hope setup. What V's are not is more controllable. I'm used to discs now and find V's horribly grabby, which is way more scarey on a road bike IMO. It is a question of what you're used to though.
Discs-wise, we're loving the Tektro cable disc brakes we've just got in. Loads cheaper than the BB7's and work better and easier to set up in our experience. The rotors are prettier too
Bike2Work-wise, you'll need to speak to any one of our dealers as we're not registered anymore. They're all better set up to deal with any upgrades you might want anyway (as Si from 18 mentioned). We're out of Long Roadrats until early June, but we have the Short length frames in. If you're 5ft 10in or shorter then one of those sizes could work in flat bar set up and we have flat bar kits in stock. Drop us a line if you want some sizing help.