Middles of the two lams I have are both crackers. Id say performance wise they are up there with the best normal bats I have used. Maybe better...who knows. Its hard for me to give a full opinion as I've only ever used them both in net sessions so fair to say neither of them have opened up properly yet coz they havent gotten enough use.
I do know that they go very very well straight away though, so could only get better with age. No problems with cracking or anything on them, but my laver match bat which is half a season old does have two cracks in the shoulder already - and its not a lam obviously.