I had a boss who said that as soon as you get a business line of credit, take the money you can and put it in other banks' checking accounts because banks have a horrible record of cancelling the line of credit right when you need it for production. Some will even see you ramping up, cancel the LOC according to their terms and then "allow" you to negotiate for a new one a few percentage points higher. He was not a fan of banks.
This is very true. You want your business diversified across banks.
Personal bank, separate business bank, separate lenders. Drawback these days is you have to provide lenders with access to your accounts. Essentially you are signing away your freedom to the slaveholders. AMEX requires access to your business checking account, not just proof you have one.
“To determine eligibility for an American Express® Business Line of Credit and to move your application forward, you will need to link a business bank account to your application.”