Yep, there are other things to consider, which are not specifically related to product design, but to M.Des in these institutions, which might be factors worth considering.

One is that the fees at NID are very high compared to those at IITB. It looks like NID being autonomous, has to generate its own revenue, and one way of doing it is to jack up the fees. Second, there is no hostel accommodation for M.Des students at Ahmedabad campus. Third, there's no concept of teaching assistantship at NID, whereas the same is available at all IITs. Fourth, the M.Des course duration at NID is 2.5 years vs. 2 years at IITs. Fifth, the IITs, being primarily tech institutes, have vast tech resources in the same campus. For example, I notice that the Mechanical Engineering department is adjacent to IDC, IITB. That's important from an industrial design perspective.

Dear Mark

Both of these institutions, IIT and NID, are among the best when it comes to Design programmes. These are among the premier colleges that are known for offering good placements as well. Every year, thousands of aspirants appear for the entrance exam conducted by the respective institute. There are about 100 B .Design seats at NID, while IIT Bombay and IIT Guwahati tentatively have about 30 and 45 seats respectively.

The basic essence of BDes. program is same in all these three institutes i.e. NID and IIT Bombay, IIT Guwahati, since the nature of degree which will be offered at the end is same, i.e. Bachelors of Design. Now what are the intricate differences between BDes degree as it is offered by NID, IIT Bombay and IIT Guwahati, can be known from the way this programme is structure at these institutes:

• NID: There are about 15 seats in BDes Product Design at NID. The program comes under Industrial Design department, so you can expect to develop competencies synthesizing industry needs, practical problems and designing. It is a four year course. Besides Product Design, NID also offer many other specializations like Animation design, etc.
  
• IIT Bomaby : IIT Bombay offers a dual degree programme of MDes and BDes, comprising 5 years. However, you will enter BDes program only, and the option to go for dual degree will become available only at the end of 3rd year. IIT Bombay also offer many specializations, but at MDes level only. Some specializations include, Industrial Design (in consonance with product design), Visual Communication, Animation Design, Interaction Design & Mobility and Vehicle Design.
• IIT Guwahati: Unlike NID, IIT Guwahati doesn't offer any specialization at UG level in BDes. The B.Des degree here comprises imparting of knowledge of design in all areas spread across four years.

As you can see Mark, all these design institutes are well-known for imparting quality education and offers BDes, there are slight differences in the structure of which they offer BDes programme.

Besides that, I would also like to tell that NIDs are known for offering good campus placements to design students. Top design companies recruit from here. After completion of B.Design from NID, the average salary you might get will be around Rs.7 lakhs per annum.

Hope it answers you.

All the best.