So I'm fine with this change, but it's important to note that the server has almost the exact same code, and it exclusively uses .Solid() rather than .empty() (in fact, there is no .empty() method on the server side, because nobody bothered to implement it). So we should try and by symmetrical here, regardless of the decision.

Personally, I would be in favour of leaving both, but distinguishing .isSolid() as a pure physics property that should not be used in any rendering code, and .isNotDraw() or .isInvisible() or something as a pure rendering property that should not be used in any physics code.