these 2 ecu ... well in rom wise p72 is better .. rechip how ever will have a disturb A/f ratio mapping..
so if you install a Apexi timer your reading with p30 rechip ecu will be at 10 ,but an unrechip ecu close loop still run well at low throttle .
if i suggest get a original rechip ecu like spoon,mugen and etc etc from japan as local ones af ratio will be at rich all the time or maybe lean all the time .
A original rechip ecu will run a proper af reading as the lambda detects it,a non original rechip locally will read it as lean and your injector will keep on pumping fuel ..
if you have a safc or e manage will help for re chip ecu .
for your question .eg and ek dont run the same harness socket .you need to make another socket harness for your eg to fit ek or dc2r ecu .this can be done .
if you using an eg ecu rechip it and run emanage or maybe vafc any piggy back will do just fine with a propper tuning