Biertourist, I know what you mean. There are lot's of people out there with huge amounts of technical knowledge and you can end up with the impression that all grain complicated. The thing is it can be as complicated as you want to make it, but at it's core, it's really quite straightforward.
I have made all manner of beers with this method and I really can't say that any style is harder to make than any other.
There is an upper limit on the amount of grain you can put into it, which will limit the gravity you can achieve, but that is the case with a picnic cooler mashtun too. You can still make fairly high gravity beers though, especially if you are going to be boosting the gravity with a bit of sugar in the boil. My Dubbelish, for example came out with an OG of 1.068 and while some of that was sugar, I also had issues with the amount of extract I got from that particular sack of malt.
I would normally expect to get about 1.060 from 5.5kg of malt, when doing a 23 litre batch. You could then boost that to 1.070 or so with 500g of sugar, or even more, if appropriate to the beer. Another way of boosting the gravity would be to add DME or you could just do a smaller batch. 5Kg in a 15 litre batch would give you a gravity of 1.085 without any sugar added.
As long as you know the quirks of your system and plan your brewing process accordingly, you can make whatever beer you want with this method.
