Just my observation, the tension loss is far less on earlier premium guts. I can speak to that as I have a good stock pile of VS from the 90's to 2000 or so. Not a great deal of experience with Lux, but the older gut handles very differently and strings differently. The extensive coating on older gut seems to be missing. Probably less weatherproof and maybe less durable, but the extra coatings in modern gut could affect tension reliability. I have handled other modern guts and the appearance is of a multi as the coatings really are apparent. Just 2 cents...
The tension maintenance isn't terrible, but definitely noticeable. I've used a few sets of Luxilon and it drops tension gradually 15-20% after a few weeks of hitting then stays at that tension until it breaks but by then i find it too loose and have to cut it out