To be fair, the trade in offers are larger this year than during P10 release window, at least where I live. So I was able to go from 10 Pro 16/256 to 11P 16/512 for something like 650 eur. It's a great deal IMHO as the SoC + modem combo is at least 30 to 40% more efficient. The phone runs faster, cooler and I don't have the battery anxiety that I got after 10 Pro.
I used the OP15 in the meantime and its ram management and (ironically enough) performance in day to day apps was somehow much worse. It unloaded apps, skipped notifications, apps took longer to open. Google have put in a lot of work into software ahead of the rampocalipse.
I'm not wanting to dispute or tell somebody what to spend their money on. I see this take a lot on reddit especially.
You bought arguably the same phone with marginal gains to CPU score and a little better battery. Paying €650 for that privaledge doesn't seem like a great deal to me...