Hi Teflon,
Gijs from Brickride here! Your track looks pretty cool. I think support is the key here.. Our roller coaster in action might look a little flumsy when it's moving around as the train goes through, but it's actually super firm.
We hope you decide to give it a go some time again! We've actually had years and years of experience, so don't give up hope too quickly!
Now that LEGO has it's own track we decided to raise the bar a bit and work on a suspended roller coaster (first results are promising by the way). So keep an eye out for that :-)