well, the entire thing should be thought from ur point of view, buddy...
first of all, u shud answer the question: how important is an MBA to u?
...and secondly, what u expect to gain from the MBA?
if u just wanna go to the top three coz. they get the best students and u'll have them as ur batchmates, then i m sorry to say that ur decision isnt the best one, coz. a lot of brilliant students miss the A,B,C bus due to one bad day at CAT or the GD/PI and enter L or K or I and a lot of average/above average ones make it to A,B,C.
in short there's not a lot of difference in the batch profile across the IIMs.
..and if ur criteria is is the higher average salaries at the Big 3, then again u havent thought deeply coz. if the Big 3 have average salary as 7.00 lac, then the Smaller 3 have it pegged at 6.0-6.5 lac, again not a real big difference, atleast not worth wasting an year for that!

...and neway, whether u land up at the upper half or lower half of ur batch, it totally depends on UR performace and not on the institute. i guess u understand what i m talking bout.
..and if its the huge sports facilities u r talking bout, believe me they r not going to make much impact on ur future as a manager. all other facilities r equally available at L,I,K
...and if u r conscious about the rankings, then IIML has always been at no. 4, which is not at all bad.
...and if u just want to be gutsy, then i would say its better to be sensible than gutsy...wasting a WHOLE year of your life for a gain which may or may not come and even if it comes, it may or it may not be a gain at all!
so think sensible and act. the brave act isnt always the best act.
its like u want to save a person from drowning in the river and u have two options:
first: u urself dive into the river knowing that u know swimming, but believe me life saving is a different game altogether.
second: the person standing next to u is a professional live saver.
i think u would be rational enough to inform the live saver bout the drowning man!
if u would have thought otherwise, then i think u should forget IIML and prepare for CAT again.
gud luck to u.
bow.