However, as a fellow Coinbaser, I'm not tempted to switch just yet.
Why even consider switching. I would imagine these 2 giants having narrow margins and highly competitive where you save a few dollars buying from Coinbase one day and on Circle the next day. Those with accounts with both can have the benefits of greater flexibility, greater liquidity(on those days that coinbase locks out new orders) , and the ability to shop between the two for slight savings.
They are both located in the US so once you have one, there really much of any privacy protections with a second.
I would warn that users who keep their coins in hot wallets will be responsible for capital gains, while users who withdraw their coins right away can choose to fund drones dropping bombs on villages of children or not.
I don't see why people wouldn't just use both either. There's no downside to it. Either way you're in the same listing for the KYC and AML, and you should have to submit the same information to both so it really doesn't matter on that front. It's more about which one deals with customers better.
I do want to point out that Coinbase can take forever to send transactions. Sending a transaction to a wallet has taken up to 36 hours before. If Circle can do instant transfers, that will be huge.