Pure INT s&s is a great build. It works good with the 80 fire 80 bicheon 80 lightning 60 ice layout at the current cap. The only disadvantage is, you have to delevel fire for the next cap.
80 bicheon 80 lightning 80 cold & 60 fire is still a good build at this cap.
Pure INT spear needs lightning and cold maxed, as well as heuksal. Lacking the defense from the shield, the spear needs to compensate with more physical defense and a larger snow shield.
There are two very good pure INT spear builds at this cap:
80 heuksal
80 fire
70 lightning
70 cold
(taken from LockStar a.k.a. 1ronMonkey - server Alps)
or 80 heuksal
80 lightning
80 cold
60 fire.
The advantage of the latter, is that you don't need massive deleveling for the next cap, except for the fire, that needs to drop to 30.
Overall, if you look at it as a whole tree, lightning has way more advantages than fire for an INT. However, fire still has the "pro" imbue and nukes.

I'd go for the light/ice build, rather than fire/light
