One of my favorite eldar units is the warp spider. im cant remember the last time i built a list without atleast seriously considering a spot for the WSs. In large games I like having the exarch with withdraw so i can get out of
CC, especially in cases where i move into range (<= 12"

and botch my assault move out in such a way that the unit im attacking can assault or im just dealing with a fast moving assault squad.
My question now is regarding small games. In a 750 list, for example, I am often left with a situation where i could field say 8 WSs or 5 WSs+1 Exarch and this becomes a tough decision for me.
On one hand, an 8 man squad will optimize number of shots. And one could argue that there wont be that many units on the table so its easier to position ureself in a manner such that you can get out of range more easily. However, if they are caught in
CC they have essentially been neutralized.
On the other hand, I do always like the insurance of having withdraw to get out of these situations. Now ill equip the exarch with 2 spinnerets so the unit has the same firepower as a 7 man squad w/o exarch, but with 6 models the unit has 2 less bodies (i.e. earlier check for falling back and easier to kill outright).
thoughts??