S41,
A quick search got this as of 2011:
(By early 2011) work totaled more than 800 hours of testing on pre-SDD and SDD engines. In early 2010, full afterburning thrust was reached in testing of the first production standard engine
Working in DC, I followed F136 very closely in the late 90s and was in touch with the DoD guys who were pushing hard for it at the time. Basically, there were too many people around who were scarred veterans of the US's 'Great Engine Wars' of the late 70s and early 80s, when they basically bet the farm on the PW100 engine and nearly lost the lot. Reinstating competition from GE resulted in a huge drop in costs and improved performance from P&W. (The USN in particular have shown a very strong preference for GE products ever since). However, as those older guys moved off the plot, their influence waned and more vocal opponents gained the upper hand in the Pentagon.
It's my own view (and as ever happy for anyone to disagree) that the US should have kept the F136 going, not only as competition to keep P&W honest, but also to offer an alternate engine source for international sales of the aircraft. Many potential customers have lucrative and well established deals with GE for engine support work - a P&W engined aircraft is going to be less attractive for them. I also believe (but don't know for certain) that the GE engine had lower temperatures and a better surge margin than the F135 - in large part due to the quite exceptional RR technology in it.
Sadly, despite the F136 having a large UK element in it, the MoD was very slow off the mark in getting behind it. As late as 99, senior UK MoD figures declined to support it at all, even when in the States. RR were speechless.
It seems that the F136, having been funded by Congress for many years against the wishes of the Pentagon, finally succumbed to the wider budget issues with the F-35 programme. In the end even Congress just could not find the money to keep it going. There are some good reports, with figures, available on the US Government's GAO website.
Sadly, I think that it's a goner, unless the F135 engine hits a really BIG problem.
Hope this helps a bit.
Engines