should i feel comfortable buying Lumin? Is it really a Linn product?
It is most definitely not a Linn product. Essentially what they did was see what Linn were doing with the category and their Klimax DS at the time, and attempt to copy it in terms of build, architecture, etc.
I think Lumin has done a good job at trying to compete with Linn and as far as overall product build, support, and performance they are something worth considering, and I wouldn't personally feel uncomfortable purchasing and/or representing their product in the right application. However, to consider something like a Lumin without also looking into what a Linn DSM can do (and how they perform), along with other more established HiFi brands such as Naim, Sim Audio Moon, T+A (not as well known), etc. is sort of leaving a lot on the table.
Of course I am speaking of all-in-one streamer/DAC combos, getting into mixing and matching streamers and DACs is a whole other ball game.