Northwest as VdH are cartridge builders with all the know how and skills to rebuild cartridges, obviously that can't put in exactly the same condition the 180 as an original one.
The Lyra designer here and in other threads already left very clear how cartridge manufacturers works and its advantages against re-tippers.
Now, the more important issue is that you are really happy with your 180/150. Just stay that way till you find out a better cartridge for your system and music/sound priorities.
Btw, if can be true that a tube cantilever can has lower wiegth than same material in rod way exist no true facts that can tell us that hollow cantilevers always are better than its rod ones. Both have its own kind of resonances and we have to think that that hollow/tube or rod characteristics per sé does not defines the overall cartridge quality level performance. Tha's why we have very good performers with hollow material cantilevers and very good performers with rod material cantilevers.
That's the same as when in other thread we analyzed the best material for cantilevers and with scientific facts was not the berylium ( as many people think. ) the best one for that specific work but diamond followed by boron.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.