I might be one of those you've read who suggested that support is good. My reference for the level of support is different from yours, I believe. If I get an answer in a day or two via email, from an operation on the other side of the planet, I consider it superior to an answer that takes three, four, five or seven days to arrive.

It's great that they will swap out your mainboard. It would not be a surprise to learn that another manufacturer attempts to evade similar responsibility.

The modification of the extruder assembly pretty much falls on your head. Attempting an unsupported modification to an established product is often risky. I hadn't seen any reference to the system you've described, which means I can't comment further on that mod.

If you decide to replace the mainboard with a concoction of your own choosing, you're opening a new can of worms.

I've had pretty decent results with my X-max but don't plan to jump into any modifications, other than to swap out to test the high-temp extruder for some first-time nylon prints.

Good luck with your repair.