If you look at the BJCP specs for the stout types you'll see there is a pretty large range depending on the style. Sweet/milk stout for example is quite low on bitterness. Though 17 is definitely below my personal preference, I think sweet stout starts at 20.
Since the addition is just for bittering, as long as you use enough to get the same bitterness the beer won't be affected much (I doubt you'd be able to tell).
For the most part, yes. Some hops will give you more flavour than others even in the bittering addition. I usually use Galena now because it has a high alpha acid percentage and also a fairly neutral flavour. It doesn't make a noticeable difference that I've been able to detect.
It's supposed to give a smoother bitterness so I'd say it's worth a try. Give it a shot and let us know how it turns out!
The mouthfeel is outstanding, though, and I can see how this would be a good stout without the ester overkill, although I think I would like a little more roast.
Just wanted to update this. I tasted this yesterday, after about a month in bottles, and I was, apparently, wrong. Tastes like a chocolate-covered banana. On the upside, I could pass it off as a halfway decent Dunkelweizen, since the roasted character is so subdued.
It was the first brew in a new place and, needless to say, I've addressed the temperature-control issues. Oh well!
