Any elite team in D3 is going to have an ath advantage over most schools. Triangle utilizes ath/spd the least and wastes the ath/spd advantage you have over the opponent, ie more upsets by teams with weaker ath/spd. It requires the most lp/per of any offense, D3 can be tougher to consistently recruit that offense.
Zone is the most complicated defense. It slows possessions(less possessions in a game more chance for variability) Requires consistent recruiting of an elite center if you run a 2-3 and a 3-2 requires consistent recruiting of 2 big men with reb. Since zone defenses slow things down -> less fouls along with the less impact ath/spd has on offense ->less fouls
So harder more specific recruiting, less possessions in a game increases the chances of an upset, less fouls drawn
Sure it has some benefits, Less depth required can focus AP on a smaller group of more talented players, stamina is not as important. You can clean up the boards if you recruit right. Zone defenses generally are the weakness of fb/press teams you see at D3. You can go after those offensive players with no defense since you can "hide them" in the zone.
However the negatives outweigh the benefits and 99% of any triangle/zone team is going to be better run with a more common offense/defense.
Go try and find any consistently good team running triangle/zone or even combinations of triangle and/or zone. I can think of a few real good ones(and I'll say they'd have had more success running any other system)
If you want to run triange/zone wait until you get good at the game and pick up a 2nd team to experiment with, not for your first team trying to learn the game