I've tried various brands of chain tensioners, including Surly.

On both my fixed gear bikes my chain has two tight spots and two loose spots, even though I use Sheldon's chain ring centering techniques.

My lbs tells me that adjusting a fixed gear chain so it has constant tension at all points in the wheel and crank rotations requires a lot of time and parts experimentation.

I use dual MKS tensioners on both my bikes because, along with a work stand, they help me tune my chain to the nth degree.

Based on my experience, I would only consider MKS allen wrench tensioners.