165hz is barely better than 144hz, basically same when you consider other areas of monitor are also important. 6.9(4)ms vs 6.(06)ms, when the less than 1ms difference is rendered irrelevant by response time differences between monitors.
you will use this monitor for many months, so i think its better to spend a bit more money and get 240hz monitor. talking about difference, i can say that there is significant diffirence even between 165hz and 240hz
Do you have 144hz now? You won't notice any difference between 144 and 165. 240 is slightly noticable but as someone mentioned above it's such a small difference you would only really benefit from it if you were a pro. It's better to go for a 1440p monitor with 144hz.
I just switched
Gameplay wise I didnt notice a difference
But I was surprised when I did the reaction test (because someone posted here) and it dropped 15ms avg from what I remembered (190ms avg to 175ms avg)
Only you can tell if its worth