Recalling (not personally) events surrounding how the Arrows F1 team demise unfolded maybe I'll just leave that aspect alone.
I have used interpart expressions in the past for passing parameters between files. Part deformations do something similar in a more manageable and reliable way after a fashion, (that is they do more than just interpart expressions). Anyway both of these methods work well enough. The consequences that come about if upon loading the assembly a vital part cannot be located are usually minor; just a warning message at most. You have the opportunity to remedy it quite easily by manually loading the missing part for example. So for all your purely geometric needs it works pretty well.
You used to have to load components fully and/or avoid partial loading of you used interpart expressions under earlier versions of NX. I think that ticking "load interpart data" in the load options may alleviate that, but I'm not entirely sure if it deals with just wave data or picks up on linked expressions as well.
You might want to test this, and I know it is a bummer if it proves to be still a problem, but we previously stopped users from adding assembly weights to the drawing in the manner you described. The reason was because whenever a component could not be located the drawing would refuse to allow you to open it. This was being done by taking a body measurement to store the mass data under expressions in modeling, and using that as relationship based note on the drawings in the form of "<X0.2@mass> Kg". Now I have just tested one of those old drawings in NX-5 and it appears to be perfectly stable. Being able to report mass in this way is a pretty desirable thing so I'd do it anyway with the proviso that you can always delete the mass notes if they start to cause problems.
For the non-cumulative masses of individual components we just use the parts list.
Best Regards
Hudson