i'm coming off a 2013 trashcan macpro, bought 1st release. Both my 2007 tower and my 2013 trashcan lasted 7+ years for me. i went with the M1 Mini b/c i refused to buy a pro for $5-6k, cost/benefit not enough for me. I am in with the understanding that this is a 1-3 year machine for me and at the price point, I'm fortunate that sub-1,500 isn't an issue for me in that timeframe. I like the rumors of a 'smaller' MacPro in the works, hopefully in the $2-3k range, might be tempted. I've been running new M1 with 16GB ram for 2 weeks now and haven't had an issue. Handbrake maxes CPU but it's built to do that. even my mac pro got to over 90% with HB. same conversion time, so I am thrilled.
I have also a 12-Core Mac Pro 2013, 64 GB RAM and 1TB SSD nVMe Drive. The M1 Mac mini out performs the mac pro 2013 in many areas (not all of course) and is working better (generally) on FCPX projects. It does not totally blow away my mac pro 2013 or replaces it...but...generally it replaces it in many tasks.
"if" the mini pro comes out (I am a doubter) that will be the perfect "in-between", but clearly the iMac that comes out will blow away the Mac Pro 2013 for sure.