I am also using Markus, until I changed to a chair from AMOffice and got a lot of issues. And now back to Markus for now.

I can vouch for above comments. For a budget chair, I think Markus is pretty solid, it's an all-rounder.
The lumbar support might not suit everyone's body cause it's not adjustable. The head cushion is just a nice addition, however it's a large chair so for me, as a woman, it overshadows me and i found myself with no support on my neck. But not much of an issue really.

But overall, the quality is good, sturdy and something you would expect from a RM500 chair.