I'd be interested to know WHY you would have a cap on the amount deposited as, assuming that you are in business to make money, you must be paying your depositors less than you can make lending it out? Isn't any (clean) money good money?
I would say that there is a risk that you'll irritate your rich customers who'll say "If my money isn't good enough for you I'll take it all my business to a bank where my money is wanted".
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This is my opinion; it is not legal advice, nor the view of my employer, and it may change tomorrow.