Don't know how I missed this thread, but I don't slow down here much.
That said, I have plenty of 41 experience, but at the moment I have to many irons in the fire to get out notes and such.
I will say this, I have done quite a bit of playing with the newer MP 640 molds. I have had the Lite version with 296 up to just over 1600fps and the heavy 220gr version rocking along at a comfortable 1300+ from my 7.5" Redhawk.
Hope to get back ASAP and post up pics and results.