ultimately preignition works just like it sounds. areas where heat and pressure can build will per ignite the mixture before the flame front from the spark can burn through it. so there are two ways to counteract this problem. 1. is to have zero quench, have such a large gap that you don't get hot spots and not localized areas of high pressure in the chamber. 2. is to have ideal quench and then you basically smother the preignition because there is no room for the fire to start. just like covering a carb with a rag to smother flames. same concept. so in terms of your dish piston and the one thats down in the hole .100, you effectively have zero quench. and in order to maintain no preignition you want to use an open. is this good for performance? Nope, but you don't have any spark knock either. in reality if your using a closed head on a piston deep in the hole you won't have any quench anyway either so it won't matter.

now with a dished piston there are some dished pistons that have a quench dome built in for running either open or closed chamber heads. these are setup ideally for lower compression in boosted applications while trying to maximize the quench. obviously option 2 with quench is better than option 1 with no quench at all.

there is alot more to this, and i can keep going, but i'm getting tired of typing.