Lightroom :: How To Develop Presets (more Than 300) Be Converted Correctly

I have a big concern. How can all my develop presets (more than 300 now!) be converted correctly so that the changes that one of them applied to one pic in the 2010 PV are the _same_ changes the same preset applies in the 2012 PV?
 
I'm not talking of Adobe LR presets (those that are installed by default and that come along with the LR itself) ... I'm quite sure Adobe has made a good job keeping them coherent with those of LR 3.x . I'm talking about of the huge numbers of largely available (on the net) presets .

I'd like to know if they will be converted _CORRECTLY_ with the 2012 PV so that they will work applying the _SAME_ _VISUAL_ changes as they did in LR 3.x .
 
Of course I'm available to manually edit the old presets, if necessary but how?  Logically, there would not need to be a new process version if all they did was put a new UI on the same controls the old process version contained.  The new controls set values for new algorithms (fill light apparently the most obvious) that don't work like the old algorithms, and can't produce the same results, but I'm pretty sure that the same visual results are still reachable somehow!

And I still need the old presets working as usually they did as a steady coherent base for my retouch workflow...