I would recommend the Business banking for the full amount. Give that you can 'maximize' your interest/return in other forms of accounts BUT it is much more important to you as a start-up to be able to have cash at hand quickly if an opportunity presents itself AND if you are to negotiate larger deals you might have to prove that you have funds at hand.
In my opinion it's not worth the hassle and small extra income to complicate your capital structure.
In my opinion it's not worth the hassle and small extra income to complicate your capital structure.