Because there's more variety on the British side,
That's exactly what I found. The Anglo-Portuguese are a nightmare purchase to organise with 'variation'.

I always thought that, for the wargamer, it would have been better if 1st division had been two divisions each with a Portuguese brigade. How much easier would that have been for choice! Also, 7th Division is so quirky that no matter how you do it, it has a lot of immediately spottable 'unique' units. Plus you have the Light Division.
When I started out, I think I planned on the Anglo-Portuguese having about 18 infantry and 4 cavalry units, plus some guns and what not. That grew to 28 and 8 respectively. I could go further but, my yardage is all used up.
In fact, at the beginning I planned on doing the army at 1x 24 man battalion per 700 men, with large units for Guards and such, and the brigade as the command group. It was the complexity of the British OOB that led me to ditch that idea early on and go for divisions as the basic command group with one unit per 1000 men and just pick the nicer units; then have the French army OOB fall into line after the same fashion.
Having played a few games it works, game wise, at least. Though it's not a scaling that would suit all. The benefit of doing both sides, I guess, is I can say "boo sucks" to those who differ in opinion.
