I think part of the fascination with the Lumi comes from the fact that it uses lots of octal tubes (5692 and 5691) and because of that people tend to think it must sound big and bold (whatever that means), which is not the case with this preamp.
Even in its day, it was sonically outclassed by the like or Mark Levinson ML-7A (which continues to sound great even compared to the latest ML preamps), ARC SP-10 MK2, CJ Premier 7, Jadis, JP-80, etc.
That said, to me the MFA MC Reference is the greatest full function preamp ever made. It used a combination of 6922s and 12AX7s with a GZ37 rectifier tube in the power supply. There were only a dozen or so sold before the company folded so it's as rare as a hen's teeth. I've seen a couple of dubious looking prototypes being sold as a MC Reference but they had octal tubes like the Lumi and can't imagine them sounding anything close to what the real production version MCR does.