json vs simplejson? opinions wanted

json is the python standard lib for json in 2.6+. It is based on simplejson, which remains a separate lib and advances faster than the core one (and is also backported to python <2.6). They are very similar, but apparently there are some gotchas. I anticipate using json more and more in koji. I guess my question is whether we should embrace one over the other. Right now, we're trying json and falling back to simplejson in some client code, but simply using simplejson in the hub code. At the moment, we still support RHEL5 as a target (that means python 2.4.3), but I'm hoping to drop that in the nearish future, but in the meantime that means we need to at least be able to fall back to simplejson. There are mixed reports on performance. Some say simplejson is much faster, others say they are roughly comparable. Also apparently there is a bit of a behavior difference wrt unicode https://stackoverflow.com/questions/712791/what-are-the-differences-betwe... https://code.google.com/archive/p/simplejson/issues/40