Be careful with the BB checks you write yourself. (or the online mailed-checks).

They are unusual, in that they have that verification number and something is supposed to happen in order to activate/cash the check.

I've had one bounce (that I wrote to myself, to one of my CU MS accounts) for no apparent reason. Glad it was my own account and I could just adjust quickly.

I used to write them to the woman I rent a parking space from, but she requested I just use normal checks since her bank was giving her some grief about the BB checks.

My GF had all sorts of problems paying her mortgage, since the cashing bank encountered an error attempting to cash it, and in response they shredded the check (this was a ridiculous chain of events, but it's true). It took about a week for BB to release the funds for use again. By then she has sent in a regular payment.
The following month she attempted to use BB's online mailed-check bill pay, and that was even worse. The way they put the payee's name it was flubbed, and again didn't go through. She badmouthed BB for mortgage and never again tried.

One thing I really like about Simple is that they show you what the actual check will look like that they are going to generate, so you can troubleshoot things in advance. Amex/BB could learn a lot from that methodology!