I would thoroughly recommend mixing things up - always worked in big company, try a startup. You will be surprised by what you learn about the job you do, and it will challenge your abilities. It may take time to adjust in either direction, and you may find you prefer it the way things were but at least you will know for sure.
Of course, you don't have to quit your job to do things differently! Spend some time analysing what you do; how you do it; what you need from your job (don't pick the easy option "I need a course"); most important of all look at what don't you do. There are a couple of great ways to benchmark your product management skills against your peers; review job adverts for your current role (or the one you are looking at fulfilling) alternatively use the Pragmatic Marketing Framework and their Annual Survey to perform a self appraisal.
All it takes is that seed to crystalise the way forward...
Not involved in win loss analysis, get involved, even if it is eaves dropping in on the calls.
Doing the occasional roadmap? Set yourself a target for the quarter, sales will soon start calling upon you when they realise the value you can add. I have done more roadmap presentations to customers in the last quarter, than I probably did in three years at Neverfail.
Blogging is pretty much part of product management these days, but I had never done it before I joined Citrix. Why? Because it was never expected of me. I had thought about it, but to be honest I was too maxed out to start trying something new, so I just left it to Marketing. That all changed when I joined Citrix, I don't suddenly have any more time in my new job, but Citrix expect me to blog about XenDesktop (especially in the run up to the launch of Excalibur). The important lesson, I have realised the benefits of it when it comes to promoting products.
Learning new skills, doing things differently is essential if we want to avoid the pitfalls that lay in wait if we become complacent. There is nothing worse than thinking we know all the answers - because no matter how experienced we become the answers always lie outside the company. If you aren't constantly thinking "what don't I know?", "why is this true?" are you really thinking about your customer, or your market problems in the right way.
--- Challenge yourself it is worth it.