I have literally never seen a circumstance where 3-2 is better than M2M against LI.
http://www.buzzerbeater.com/match/35974595/boxscore.aspx
Here's an example of me playing 3-2. Now you can see where some believe it is effective, my SG's PP100 were bad and he shot 18 shots...so it did it's job in that regard. It even held me to a mere 39 percent shooting. The problem? 21 offensive rebounds compared to 6 the other way.
The guards did a good job at stopping the ball at going inside but 3 things happened
1: The SF received the ball in good positions and was able to score inside effectively at nearly 50 percent. This SF was actually a PF with good jump shooting ability and obviously very good IS. He not only was able to get inside but he got to the line 5 times. This is definitely an instance where the opposing team could've used some ID there rather than the OD.
2: The SF playing PF could shoot from the outside, so even if he didn't receive the ball in a good spot, he was able to shoot against the zone.
3: The C had 10 offensive rebounds, and even though he didn't get a lot of shots he was able to get a ton of putbacks and it hurt the team just as much. He also was able to pass through the zone and became the main facilitator(nearly all of his highest assist games were against zones.)
Now the shooting percentage is actually...even skewed for multiple reasons.
1: The SF that went 9-20 was coming off of injury, he was only in respectable game shape. Had he been on proficient form his ability obviously would've been much greater.
2: The starting SF playing PF who shot 50 percent went out with fouls, and was replaced with a traditional big who couldn't shoot at all, he went 1-8.
3: His big men blocked 11 shots, nearly all of them layups and dunks, something the 3-2 zone is known to give up. His big man in particular that blocked 7 shots has an inordinately high shot blocking stat....higher than most train it to.
Long story short. Don't play 3-2 zone against LI.