well for starters, the fight value isnt really useful as ur elves are better or just as good as most captains, and if you are fighting someone like a captian, then there is a fair chance that he could kill ur precious guard.... so let ur capt take the likes on them on and have spear and pike support, a sure win against captains (although any evil thing with f6 is really dangerous and should be dealt with care (as in shooting it to pieces and piling on ppl
![Very Happy :-D](./images/smilies/haha.gif)
))
so the reason i would take them is for the pike support, which is really good for elves as it allows you to bring more attacks against your foe (when you get to 3 attacks for a regular soldier you really see that f5 shine) and is sooooo good when used with heros
so after all that the simple answer to your question:
if you are going against an enemy that has only a few big hitters(like goblins), then take only a few (like 2-3), if you are going up against armies with more dangerous stuff (i dont know.... like if they had f5 captains and spiders ect...) then mabye 3-5
so never get too many as they are best used to give your army a bit more flexability
lol, such a long answer so such a simple question