At least in the OP’s case it seems the requests are infrequent. I understand your point about the 11th request, but at that point what % of your customers are impacted. The tail latency is always an issue, PC is a good way to solve that.
PC is definitely "better". It does require you to opt-in to function versioning, but if your ops automation is good enough to make that easy, its just better. The biggest advantage over warming pings is, really, that it keeps your metrics and logs clean and focused just on user invocations, not on weird faux-invokes that are extremely difficult to filter out.
But, its downside is that its ~100x more expensive than warming pings for infrequently invoked functions (defined as: average concurrent invocations over a month timeframe between 0 and 1).
If your company has the money, go for PC. But don't feel bad about going for warming pings; it ain't a bad setup at all.
