With Lasalle board sizes and 6 infantry and 3 cav to a base will give a massed effect and you will have the added benefit of actually seeing the miniatures.
As I am a fan of smaller scales, especially in terms of mass battles, I prefer the look of 16 10mm-Miniatures on a 4x2 base.

And painting the numbers of required miniatures in 28mm would probably be another neverending story.
As so often a matter of taste...
....and of the circumstances. If there had been players in the vicinity, who knows, perhaps I had used 15, 20 or even 28 mm. But as so often the people talked about the possibilities (also of 28mm plastic), talked about the great look of the miniatures, talked about the own interest in the period etc. ... and until now they keep talking;)