a lot of it depends on my team composition, if i run with a big sf, i generally run a 2-3, and with a guard sf, generally run a 3-2. so the deviations from the base depends on the opponent and also how suitable i think each option is for my team. usually if i have a guard sf who is like 90 ath/def i figure he can't really hurt me in the 2-3 and if i have a pf type sf who is like 90 ath 60 spd 90 def, i figure he can't hurt me in the 3-2. so then ill really just change it up by opponent - but that isn't always the case so how easily i change to suit the opponent definitely depends. it doesnt just depend on the 3 either, if i have a lower sb pf, i am more likely to play 2-3 to get him averaged with the sf, not the c.
note that all 5 players defend every shot in the zone, so you can't just think of it as the guards defending guards and such, but it is important to get guys averaged in ways that are desirable.
to me the biggest thing is the impact on 2pt% and 3pt%. 2-3 is easily the best 2pt defense in the game while the 3-2 is easily the best 3pt defense in the game. i think the +/- nature of playing more negative with a 3-2 than a 2-3 sort of rounds out the rebounding so mostly im just deciding if i want the 2pt defense or 3pt defense. if that desire is more important than the fundamentals of my team with respect to the 2-3/3-2, then i make the switch. 3pta is probably the biggest driver. my understanding is the defensive equations for zone include all 5 players and depend on the distance from the basket, of the shot - but not the player who is taking the shot. for that reason, i dont care if its their 1&2 or 1&3 or 2&3 who make a lot of 3s, i just care they make a lot of 3s.