For a short while I ran my Rohloff is a frame not designed for it, I was experimenting with geometry before having a custom frame built (If Thorn had been a bit quicker off the mark with the Mercury it would have saved me the trouble...)
Anyway - I used a tensioner and apart from the aesthetics and the extra cleaning and the added risk of damage it worked fine. What I didn't like was the ugly and awkward chainstay torque arm, it's the one thing that shouted these components have been bodged together. There's a growing number of frames, including Thorn's Audax Mk4, that overcome this by being designed to accept the OEM2 plate. I use one of these, along with a tensioner, on my Airnimal folder and although it can make wheel refitting a bit awkward it's vastly neater than the long torque arm.
I like the aesthetics of an EBB, I'm not sensitive enough to notice the changes it makes to the ST angle, adjusting the chain is a 5 min maintenance job that should never need doing unexpectedly. I have no experience of the sliding dropouts, though the Paragon Rocker variation seems the neatest. The tensioner works fine but IMO the system is better without, as for simplest, I'd expect to spend more time maintaining a tensioner (Including cleaning) than I would adjusting chain tension with an EBB or sliding dropouts.
