I recently picked up the 10th gen i5/16/512 model. This is arguably the best Mac I have ever owned. It got warm first day downloading, installing and indexing everything; fan noise has been very acceptable. Trackpad/palm area gets slightly warm, but nothing too crazy. It handles WOW and some of my Steam titles just fine (I have realistic expectations running games with iGPU so I haven't bothered trying ultra settings, and yes fans kick in when I'm gaming). Xcode, Photoshop, Lightroom and productivity apps (Office 365, etc.) run smooth as butter. Same thing goes for video conferences.
Battery life is AMAZING. Yesterday and today, on and off I have been browsing the internet (SAFARI), streaming some music and running some productivity apps - I believe I am close to 12-13 hours of usage - and battery has just gone south of 15%. Of course your mileage may vary if you're using Chrome (for the love of God at least don't use Chrome on the go), screen brightness, ambient temperature, etc.
I was on the fence for getting the i7/32/2tb model (the only i7 model that is readily available at the Apple Store) but I am glad I didn't. For what I use it for, this is an amazing machine and I am loving it. Unless you have a crazy demanding work flow, the new i5/16/512 model should be more than plenty for most of you out there.
I also use Sidecar actively so I haven't bothered plugging in my 4K monitor. Sidecar runs smoothly and it hasn't caused fans to kick in - so if you have a relatively new/compatible iPad laying around somewhere, you may find that a viable option if you are concerned with fans kicking in when you connect an external monitor (yes I can plug in my monitor and give you guys feedback later this week)
My next project is to install the PB of Big Sur using Parallels when it becomes available and see how this setup handles running a VM. I am sure it will be just fine.
Hope this helps someone. Cheers!