I have no idea. I don’t own a RatRig or Voron to test against. But just like with either of those, the ability to tune them is what counts the most towards speed/quality. My V4 and V5 both print really well and I have been happy with them. Most of the issues I ran into were just me learning not the fault of the printer or anything else.
I will add that at the 500mm size you want, I do think something like the ratrig would be a better option. The MP3DP uses an unsupported X rail, and at that length I think it would be harder to keep higher quality and any amount of speed