[Daedren]

The CTO already said you're ok, you have everything you need. The owner (generally) wouldn't have the technical know-how of what you actually require.

I got to work in a bank and I can say it's nothing special. There's a much increased load of compliance-related work due to how regulated the field is, but otherwise that's about it.

There's -a lot- of business knowledge to know about, and you'd make more use/need of it in a smaller bank yes, but it's not what you'd really ask of the software developer.