the lux will hit harder, but if you dont keep the threads clean, after a while it wont hit as hard as the SS, as with any metal that tarnishes you have to take care of it. the lux is aluminum bronze so it would hold up better to polishing than softer brass but as with anything repeated polishing wear it down. myself i love the look of brass but i prefer SS mods as I love the idea of someone picking it up 100 years from now, clean it up a bit and it looks good and vapes well.
I would say that if your looking for a brass mod, the lux is a really good choice bc you can easily get new tubes, and it has SS switch and cap, brass is very soft and imo it has no place in a 510 connector with the fine threads in there, or in a switch lock ring, putting brass any place that has to do a lot of threading/unthreading or has fine threads is asking for trouble bc of how soft the metal is and getting stuck to other metals. its the main reason i sold my brass chi_you and kept my SS one, i loved the mod but was afraid to use it after i got an atty stuck in the 510 and barely got it out and knicked a peice off the brass after falling over.
if you dont like taking care of stuff, get the SS one, if you like polishing/refinishing, get the lux. both are awesome mods