[css-writing-modes] Tate-chu-yoko sizing rules

Yesterday, Muarakami-san invited me to dinner with a group of 10
Japanese typographers / type designers / DTP operators. Naturally,
I put them to work on the question of the day, tate-chu-yoko.

We started out with two options, A) force to 1em and B) do nothing.
The table was split about 4-2, but two others held out for an option
C) "It depends". After much discussion in Japanese, the group at the
table came to consensus on the following rules:

   1. If 1/N-width glyphs are available, use those. Otherwise
      use regular glyphs.
   2. If the resulting composition fits within the 'line-height',
      don't scale.
   3. If the resulting composition is wider than the 'line-height',
      scale to fit within the 'line-height'.

I asked if they were ok with the implication that TCY might conflict
with ruby if the line-height were too small, and they said it's
acceptable, and assured me that these are the rules they want.

Here is the drawings we used for the discussion:

   http://lists.w3.org/Archives/Public/www-archive/2013Jun/att-0069/shinjuku-2013-06-11.png

I would like to edit CSS Writing Modes to reflect this consensus.
Are there any objections to this?

~fantasai