We installed a Petronix II and a flame thrower coil in one of our cars and saw an immediate difference performance. We liked these bacause we could repaint the coil to look like the original yellow top and the Pertonix II fits neatly inside the distributor.
We have also installed a hidden MSD6A system. This is a module which provides multiple sparks during each combustion period. Once it was added we saw a huge improvement in idle stability.
Since we are focusing on a concours driven restoration we really are not looking for performance increases but these components really helped low speed performance and this was important since we added the original style AC which can be very demanding on the engine and cause vibrations etc. A strong engine is key to making AC work well on an original type install.
Pertronix 1 is just a replacement for points and only performance improvenmnet is points start wearing first rev of engine and continuously goes downhill till readjusted and pertronix never degrades since it has no mechanical parts to wear - it inductively/solid state generates path to ground for coil. pertronix 2 provides some improvement by providing variable dwell at higher RPMs - it would be hard to measure but many state marked improvement. IMHO thats rationalizing spending their money for it. flamethrower coil is good and hurts nothing.