Anybody Heard of Mars & Co. Consulting?

I see they price themselves (note the interview with the founder is in French) similarly to MBB (which is a little bold in my opinion, but why not), and have this culture of 1 client/industry (give or take). So, that's definitely a limiter for growth, but on the flip side, also great for creating a long-lasting experience and expertise with a given client. And it is wholly owned by the founder (so not much of a democracy, I would expect).

They are almost as old as Bain ('79 vs '73), but are 50 times smaller (250 employees vs 13,000), but that's a function of their business model, I would think. All things considered, if it's still around, it must be doing something well. It also really does look like if the founder goes, either the company goes or will change drastically, so not sure how this will affect your day-to-day.

Small firms can be interesting to work for, I interviewed with a small firm a couple of years ago (70-80 consultants) and I genuinely liked nearly everyone I spoke to (except one partner and one principal... I won't expend on them here). So, I'd say see how you interact with the people there and maybe message a few alumns. It's a small company, so there might not be too many.

Good luck with your interviews!

EDIT: Looks like they have a global staffing model, his wife is head of HR (why not), and that they favour analytically-oriented people and methods (link).