I have an M1 Air, 1 tb. The internal SSD gets 3,000mb/sec (Consistent Blackmagic Disc Speed tests). I have a Samsung T7 1tb w/advertised 1,000mb/sec. I've never gotten 700. For $400 per tb or less, you get 7,400mb/sec speeds. And my Air NEVER gets hot, or throttles. Ever. Dead silent. By all reports, the M1 Pro's fan cooling systems is nearly as silent. As a musician, this scores a lot of points. Really think about that though. With a 2tb SSD on board, I don't NEED external SSD's, other than for storage; or organizational purposes ... A LaCie external SSD, 1tb, advertises 2800mb/sec. Their reputation is great. The price is $399. My money goes to Apple's 7400mb/sec internal drive. Good luck!
This is why i got the 4TB even though i won't need it till jan or feb.
i hate external drives, and the speed of even the fastest SSDs externally still stink compared to apple internal ones.