Having never played InF on-line, I can't really offer much input, but the fact that InF isn't CTF is what makes it fairly original. When you consider the InF gameplay it influences alot of things. Firstly map design, map design is very often based on an external team trying to, for the lack of a better word, infiltrate, an area in order to take the CD, the fact that the maps are based on this idea of one defending base as opposed to two near identicle bases in a near symmetrical enviroment ala CTF.
I still believe strongly that InF's strong point is in Standoff. I love team-play on Action Quake 2, it's awesome, and InF replicates that closely enough for me, they will more than likely better AQ2 with their upcoming versions, Version 3 especially.