I have my H6 Eg33 bugeye running on MS3/3x with no problem. ****ty closed loop? mine runs like factory and uses PID to maintain the desired afr when it deviates due to ethanol content.
The stock SVX ecm has no where near the features of the MS3 and if you know what your doing with your megasquirt you'll have it running 100% as good or better then the oem offering.
OP, if you need any help with the wiring aspect or would like to pick my brain/copy of my tune just PMme.