A small point though:

Before we focus too much on A123s in particular (which is obvious bacause they are in effect market leader) this is about allowing LiFePo4 for heavies, not A123s alone. There already are more manufacturers out there, some with better specs some with worse, and just like with Nicad and Nimh some will emerge as the best and some will fall short. But none of this is safety related only performance related. The current rules were written in such a way there was no possibility for any Lithium battery to be used including the ones that are not balls of fire waiting to happen. That is why I am in favor of allowing the use of LiFePo4 in heavies.

In the time to come LiFePo4 batteries will get better and better as they are already becoming more and more commonplace in electric vehicle use and DIY equipment. This has been true of all battery types and so will LiFePo4.