Love this question!
Obviously, always protect your employer’s confidential information. However, if you have done your work correctly, your messaging will inform all of the material and content you’ve developed. It would be reflected on your website, on your datasheets, on other public-facing content (press releases, blogs, etc.)
But far more important than showing what you have produced is proving the impact that it had. Showing success metrics for messaging is one of the most difficult challenges for product marketers. One problem is that messaging success depends on the collective action of all of your sales and marketing efforts - from your website to your content, campaigns to SDRs to sales reps, and much more. It requires everyone to work in unison, which does not always happen.
But to truly answer the question, we first need to understand the goal. What are you trying to achieve with your messaging? It could be more revenue, winning a larger share of opportunities, gaining greater market share, reducing churn, managing a PR debacle, differentiating from competitors, repositioning your brand, product or functionality adoption, etc.
Without knowing that, I’m afraid I can’t give you a solid answer. So go back to what it was that you were trying to achieve and then think about what the relevant success metrics are. A couple of examples:
- if your goal was to win a higher percentage of open opportunities, then measure this in terms of whether there was an uptick in won opportunities compared to the old messaging.
- if your goal was functionality adoption in your install base, start with a relatively small but representative subset of customers to educate them, then see if adoption has increased relative to the control group. (It might take some time to get results, depending on the complexity of the customer and your product...)
One final thing, it's rare that you would try to achieve your goal only through adjusting messaging. It's usually a cross-set of activities and stakeholders that drive impact.