Any disadvantage to #'tag ?

[Graham Percival]

Is there any disadvantage to using #'tag for large-scale works?  (speed 
reduction,
or some complex formatting things not being processed through #'tag)

It occurred to me that #'tag can be useful in extracting parts.  If 
we've defined
the obvious things, then we could organize a large project like this:
(placing these in separate files as desired; string quartet example)

music = {
  <<
  \tag #'(score vn1) \new Staff { << \global \Violinone >> }
  \tag #'(score vn2) \new Staff { << \global \Violintwo>> }
  \tag #'(score vla) \new Staff { << \global \Viola>> }
  \tag #'(score vlc) \new Staff { << \global \Cello>> }
  >>
}

\score {
  \keepWithTag #'score \music
\layout { }
}

\score {
  \keepWithTag #'vn1 \music
\layout { }
}


This has the advantage of keeping the individual instrument
files as small as possible, and also making it easy to extract
other subgroups.  (say, "string" or "brass" in a piece for orchestra)

If there's no disadvantage to this method, then I'll update the
string quartet template to use it.

Cheers,
- Graham