Do you recommend a Senior Product Marketer who is looking to advance his/her career and has worked at start-ups for 5 years to join another smaller start-up or a larger more established company?

I do think having a mix of both startup and large company experience is highly desirable - it shows that you can succeed in a variety of environments. So at some point, you will need to make the jump. I do believe that my mix of both worlds has made me more marketable.

Going to a larger company is great for finding mentorship and/or deepening your PMM skills, You will also get a 'halo' effect of learning more about how other functions operate at a mature company - i.e. how large-scale PM teams operate. You will also really hone your communication skills and cross-functional leadership/persuasion skills. There are A LOT of initiatives competing for attn at larger companies - you need to stand out to get the resources you need.

If you jump to an established company, you may have to take a lateral title move, or even go down in title and work your way back up. IMHO, this is not a big deal in the long run of your career. I once went from a VP-level role at a startup to a Sr. PM role at Adobe because I was making an industry shift, and I had never worked for that size of a company before. It was a GREAT decision. I gained highly valuable experience, and quickly worked my way back up to Director level roles, and then went back out to the startup world into VP roles.

A good mix of company size is important for personal growth as a PMM, but it may not always correlate to career growth. You are likely going to need to focus more on strategy at larger companies and may take a liking to it. The market dynamics at larger companies are also different. This gives you a good story to tell later on when you interview, as you would have seen how PMM works at different company lifecycles. Highly recommend. 

At the same time, you may get offered a chance to build a PMM function at a smaller company and that could offer a different area of growth and learning than the bigger company environment. 

Choose your own adventure.

I would suggest going to a smaller organization where you will have a chance to build out a team and get promoted. When you go to another small start up that let's you build a team and promotes you to Director, you have the ability to show that experience when you want to land a similiar Director role at a mid to large size company. Most Sr. Manager or Director roles require that you built out and led a team.

It's much easier to get promoted in your current company than jump from Sr. PMM to Director while making a move to another company.