I don't know what tsfc is, but I measure a turbines performance by many things.
Thrust is important, but let's face it you can get as much thrust as you want out of any manufacture these days.
For me performance is more about:
Reliability, this means in the airplane. Will the fire keep burning and turbine keep turning.
Customer support, if I do have an issue, will the manufacture be there for me?
Availability, can I actually get the engine in a timely fashion, if sent in for parts can I get it repaired quickly?

I don't care what the thrust is, if an engine has to go back regularly because of problems that is crap performance. I don't care what the warranty is, if it is continually going back for warranty issues that is crap performance. And to some extent, I don't care what the price is, if I can't get one that is crap performance.

I really don't know what amt customer service is like, I have never had to do anything to any amt except put fuel in. I've never had anything but instant response from Barry at kingtech when I did have a kingtech. In fact all the engines I've had have been good. My jetcat is in fact the only engine I've had any problems with. On the rare occasion I was able to actually get a hold of Bob Wilcox, customer service was great. But any other time I've called, and had to deal with anyone else there, I was ready to sell the engine by the time I got off the phone.

Oops, I had some issues with booster engines as well which were eventually rectified but that was a hassle too, however, the booster engines I have run have all run like a freight train.