Yes, you can have any ECU. The 525 is the best option for simplicity and reliability.
Thats arguable. LOL The LS3 takes mods to make it live. If you can run any ECU than I would for sure run the LT1. Its been very reliable. Our issues have nothing to do with the engine itself. The thing is strong and does not need better oil pump, timing mods, etc. Right out of the box its solid.
Its not like the LS3 525 does not have issues. But I get that its hard to change mindset and do something different.