I have had a lot of fun w/ mescolanzes and find them to be an efficient use of space.  They require a little more room lengthwise than that of a hands 4, but considerably less in width, compared to 2 lines of hands 4.  Similarly, 2 sets of 4 X 4 if 4 sets of hands 4 is too crowded across the width of the hall.  Your space btw sets, and the wall is reduced from 5 to 3 in the latter example.  It is also a great way to combine the 1st line to form w/ the latter line, which can have some obvious advantages for mixed level trail buddies, instead of lines that often tend to be more distinctly homogenous.  

I personally do not care for full heys in tight quarters, but half heys are easier & more satisfying.  Down the hall is tough if you are short on hall length.

Once we learned what I remember being called a Portland style (?) promenade across the set, by Lisa Greenleaf, while we were fairly smushed.  As I recall, the two cpls walk 2 steps straight toward each other, then both turn sideways (to their R 1/4 as a single unit, still facing your Ns) slide past the other cpl in the center of the set, and once clear, turn another 1/4 to the R, still facing them and now the direction you came from, and back out to the other cpl's original spot.  Satisfying move and compact crossing in a promenade.

Just a few thoughts w/o having cards handy.

Can't wait to hear more.

-Paul