It is worth spending a few quid more on a sprocket with a wider contact area with the free hub. These tend to be stronger, less resistant to twisting and kinder to your freehub.
Superstarcomponents stock a decent set - its the one I will be using soon.
My personal experience of tensioners with jockey wheels is bad - I prefer the sort with a guided pulley. Those with jockey wheels tend in my experience to derail too easily.
The surly type i had was a jockey wheel with a large flange each side of it to feed the chain onto the jockey.
Not too keen on the roller type :? ,im not a fan of things rattling their way round.
How can you tell if your drivetrain is off by a bit if you cant hear it over the noise of a chain rattling across that roller :?