I just switched from 16" 2019 i9 -> 16" M3 pro and 2 weeks later still stunned at how amazing of a machine it is. I do a lot of c++ dev for $dayjob and my current project which took 1m45s to full rebuild on i9 is down to ~25s on m3. Without a fan turning on or barely getting warm. Its _magical_. I still get caught off guard by the chassis being cold when first placed on my lap.
The issue is that the 2019 MBP16 were crap. Especially the higer i7/i9 models had thermal throttling issues when connected to an external monitor.
My 3000€ i7 mbp16 2019 recently died and I replaced it with an "interim" base model, 650€ MacMini M2. The jump is huge, that freakin Mini beats my 3yo (I bought it in 2020) decked out MBP that constantly spun fans. While intended as Interim until M3 MBPs where announced, I see no reason to upgrade right now.
I remember getting this jump accidentally - I bought a M1 Mac Mini for porting stuff too and for testing, and building on it was twice as fast as my 2018 15" i7. And it was silent doing it. Pity it was only the 8GB base spec, because it would have made an amazing main machine!
I used to have a 16" i9 for a previous job. It was absolutely terrible. Any sort of build process would cause the fans to spin up. It sounded like a jet engine taking off. The corporate malware scanner didn't help it much, either, as it slowed processing even more.
I just disassembled mine a few days ago and cleaned it out completely. Before that, my fans would literally max out with almost nothing running. Now, they stay silent pretty much all the time (until I do something really intensive). Still thinking about an upgrade to Apple silicon now, though.
