This was a trial game, and I chose Busaco as being not too big but doable allowing plenty of time for page turning. In the end, Busaco (65,000 men per side) is probably near the bottom of the size of battle that these rules are intended for. Waterloo, Austerlitz, Dresden, Wagram or Leipzig are entirely doable.
As Vlad said while we were playing, the rules are a bit disorganised, and important aspects are either in the wrong place or not mentioned (How you represent a single Reserve Cavalry Division attached to the C-in-C for example.) The only consolation is that the author is very proactive on FB, and his overnight input confirmed that we did things mostly correctly.
Conclusions. It needs a better QRS as an absolute minimum, but I can see us giving it another go soon.