I had a question about full ionization, but I may have answered it from my tests. I thought that once a ship was fully ionized it couldn't be ionized anymore. If my hypothesis from my tests is right, then that's partially true. The ship's speed (in my evn 1.1.0 ships' speed is definitely affected unless using afterburners), turn and acceleration aren't negatively affected anymore after a ship reaches full ionization. However, it looks like ships can continue to "store" ion points which must be dissipated.
Ex: my manticore with a deionize rate of 30 (should be 9 points per second I think) and a max ionization level of 225 got ionized by 4 ion cannons for a long period of time (maybe 10-15 seconds). It took just over 2 minutes to fully deionize. That should mean that it had somewhere over 1000 ion points to dissipate.
Ex 2: the same manticore was ionized for a much shorter time (maybe 5 seconds). It took about 1min 10sec to fully deionize. Should mean it had around 630 ion points to dissipate.
note: the plug i'm using has a stock manticore with shields of 1550 and armor of 1360 and ion cannons doing 60 dmg/s to shields and 30 dmg/s to armor - that's how it can withstand that long a time under 4 ion cannons. …The damage done to my manticore doesn't really seem to add up for that amount of time under fire (i had somewhere around 90% armor remaining after the long time under fire), but whatever.