It depends on the other options available to you. ABM graduates are eligible for many of the marketing and operations jobs that normal PGP students are. Choosing an ABM at any of the top IIMs (including IIM Lucknow) is a better option than a general MBA from a tier 2 business school. Even if you take a drop for CAT, it will be a waste of your year. In an MBA, your college tag makes a big difference. In the long run, the IIM tag will benefit your corporate career a lot.