Re: 2012 RG350MZ vs RG550
I'm afraid you're going to be in the minority on this one. I doubt if many on this site would say the EZII is "on par" with the Edge. It's not a terrible trem, but it's no Edge. I don't know what you're talking about warping - I've owned in the neighborhood of 75 of the older 1-piece wizard necks, and NEVER had a warped one. The neck profile is also quite different. Quality of hardware, electronics, quality of materials, overall QC, etc. Not the same.
You're getting into the Indo vs MIJ debate that's been beat to death on this site. There's no such thing as something for nothing, and the RG350 is an economy guitar for a reason. There's also a reason why the RG500's are still (20 years later) one of the most recommended guitars on this site.
Hey, if you're happy with the RG350, that's great! They look good and for a lot of people they do just fine. But I don't believe they're on the same level. I'll stick with the RG500's.
And yes, I've played all of the above.
EDIT: If I had to pick the true modern day RG550, I'd say the RG1570. Low end of the Prestige line. Still the better quality hardware and materials, just in a no frills package. I see the Indos as more like the modern day EX series (though Premiums are somewhere in-between).