AcademicsEveryone (including me) thought that studying after a gap of 4 years would be really difficult. I had been away from academics for such a long time. Plus I was enjoying a well paying job in Pune. But surprisingly I found no difficulty in dedicating my complete time for study. In fact I think I was at an advantage over people who had directly come to M. Tech after their engineering. They seemed slightly fed up with studies. After all, they didn't have any gap in studies from the last 10 to 15 years. Me on the other hand, I was enjoying the classes, the assignments, the exams. The 4 year gap felt like a 4 year vacation I took from academics and so I felt I was more enthusiastic and full of energy than others. I hope this is the case with everyone going for mtech after a gap.
Besides, if you have done a lot of C/C++ programming in your professional career, it might help you with the large number of programming assignments we get at IITs.
PlacementsThe fact that placements are not a problem for mtech CS at IITs, I have discussed in my older post here. But if you have a few years of experience, you would be thinking, will they consider my previous experience for placements? Will I get any advantage over others who have come directly after engineering? Will I be given a higher salary/designation than others? Well, I have some good news and some bad news. The bad news first. You won't get any practical advantage because of your experience (at least at IIT Delhi, don't know the details of all IITs but I am guessing the placement system would be same). That is, you have to qualify for the CGPA cutoff and you have to appear for the written test with everyone. There is no separate criteria or written test for people with experience.
The good news is, once you are through the written test, your experience might help you a lot during the interviews. There is very tough competition at IITs for placements and people are not shy about displaying anything worthwhile they have done. So having a few years of experience definitely gives you an edge. Of course, it still doesn't guarantee anything, but it is a great help.
I have not heard of companies giving a different profile or a higher designation to people with experience. This is somewhat offset by the fact that your experience might help you get placed into a better company.
There is one thing that I would like to add though. I used to be under tremendous pressure for getting good a placement because I had left a well paying job to go for mtech. Imagine, leaving a good job, going for mtech and then ending up in a job of lower value than the one you left. One feels like he is competing with himself. Perhaps this pressure is unavoidable for someone coming after experience.