Do you think product marketing performance should be judged based on KPI's or are they more guiding metrics to inform where to spend time and resource?

Product marketing performance should absolutely be measured, and both the outcomes and measurement parameters should be well-understood from the start to avoid a whole lot of folks running around doing stuff without a clear sense of "why?" and "how do we know if it's going well?". Every industry and business is going to be slightly different, but any PMM metrics and measurement should ladder up logically to the top 3-4 company objectives or goals - like grow revenue by X%, boost net customer retention by Y% or enter Z market with a compelling, credible offering. Once you have the top 3-4 company objectives or goals (and if senior leadership can't agree on those, you might be in trouble), the next step is to determine exactly what the product marketing team is doing (and, subsequently, not doing) to drive to those goals. For example, if a top company goal is to grow revenue by X%, the PMM team isn't responsible for owning accounts or closing new opportunities per se (that would be sales) or ensuring customers have the support they need to drive expansion and prevent churn (that would be customer success), but there is a lot that PMM does along the way. Don't let that work get lost - measure it so you can manage it. Messaging is a fundamental responsibility of PMMs, but don't just measure task completion (i.e. messaging docs drafted, reviewed and delivered), measure whether or not that messaging is working. In a modern PLG SaaS environment, messaging is critical to getting prospects not only signed up but using the product. If the messaging isn't landing (too vague, wrong audience, chock full of jargon), sign-ups will struggle and adoption will be even worse. But if people actually understand how your company's product will help, both at the top of the funnel and while they're finding their way around post-signup, that's a strong signal that messaging is working so take those KPIs for the PMM team. It's the same thing with sales enablement work like First Call Decks (FCDs), competitive battle cards, sales plays, demo scripts - the kind of work we tend to spend a ton of time on as PMMs. Don't just measure the completion and delivery of those assets (most GTM orgs are swimming in undiscovered or out-dated artifacts cranked out by PMMs), measure their impact on opportunities both being created (which in a SaaS/PLG team is measured by self-service customers "crossing over" and in traditional enterprise sales is measured by BDRs/SDRs creating an opportunity guided by assets likely created by PMMs) as well as opportunities progressing to close. Product marketing teams should be creating assets and programs that rally stakeholders, enable champions and fend off competitors during RFP bakeoffs to help drive early opportunities to close. Track when and where sales teams use those assets and programs and do cohort analysis to show the impact of when they're used vs. when they're not to help scale GTM and evolve past an account team "hero ball" culture that will likely have PMMs scrambling around like short-order cooks.