i wouldn't play this game without the darthmod and the additional units mod. its just so much better with them.
with the darthmod, instead of line infantry having 150ish men they have around 300 and other units have up to 600 men in them. it also makes the weapons more realistic, improves the BAI and incorporated the famous blood and smoke mod.
I enjoyed a lot of mods for Empire: Total War, but for some reason version 1.4 just completely reverted the good things that were in the previous patches, or so it has seemed to me. I think I'll just stick with Europa Barbarorum for Rome: Total War in the meantime.
Rain didn't effect the firearms in the original Empire:Total War? That seems regressive, since rain could dynamically disable your gunners as far back as in Shogun: Total War. Sporadic showers meant your fire support was constantly flipflopping between functional and defunct. I forget if it had any effect in Medieval 2: Total War though.