I'll be interested to hear others weigh in on dropping a bolt thru the neck of a shen.
From my perspective, there's part rationale and part taboo. There's definitely a point at which removing wood is simply going to weaken the whole structure, but I do think there's sometimes a place for hardware if used correctly. There's a big difference between Jimbo fixing it with an impact driver through the fingerboard and a luthier's calculated, reversible repair. The spline repair you did on that cello looks great, and I wonder too if that's not an option, but something that I don't personally have the tools (or possibly the skill
) to execute well, and I wonder how much more bench time that would require from a pro luthier.