I'm assuming you're talking about a sprung loaded chain tensioner so you can shift chairings on the move in which case, you'd be better off using a real deraileur system with probably a single chainring at the front.
A better alternative might be the S3X 3 speed fixed gear hub from Sturmery Archer.
Failing that, try normal fg. I know you mentioned hills but you'd be amazed what you can climb once you get used to it. I actually live IN the hills that surround my city and it's only the extreme stuff that people with lots of gears suffer on that defeat me.