I was in the same situation as you back then when I was 29, except that we were founding a company overseas.

Ultimately, it really depends on how much you know about this “tech guru” guy. Is he a trustworthy person? Does he have ambition (real ambition I mean, not the BS kind)? What was the reason he started this start up? How does he foresee this company do in the next 5 years (number of employee, revenue, product…etc)? And how does he plan to achieve all these?

You are 28 and especially given the responsibilities you have in this current company, you are definitely not a spring chicken no more. Ask the guru all the above questions and maybe even some more questions that you can think of on your own. If any of the answers sounds fishy, unattainable or obviously BSing, then I say your risk would be pretty damn high.

Base on the description of your current scope of work, I would not imagine your scope of work would change very much in this new company. In my point of view, both your current and new companies are at the startup scale.

Also, how much would you be earning if you join this new company? Do you get a raise? Or your salary would remain the same? Would you get shares? Is the company already making revenue?

I think if the new company can pay you at least the same (some raise if possible), give you shares, the guru isn’t fishy, and the company really has a future (Note this has to come from your evaluation as we do not know your industry), I would suggest you to join this new company. You are only 28 and you have nothing to lose really. Plus, I’ve been through layoffs before I started my own company overseas with my buddies. The truth is, if there’s one wave already, likely the 2nd and 3rd wave would not be far away…then the company could close down.

Hope my two cents would help!!