Re CIBCI would have to agree with Cody that CIBC has been excellent. Every other bank or trading platform has the fine print however CIBC has the least restrictions. $10,000. That is it. What is not to like. If you have as much as you say then the annual cost is less then one trade in and out. TD limit is based on $100,000 and if the market dips your account under it then they back charge, E-trade has nice rates however if you drop below a certain number of trades they backcharge as well. I like the fact that I do not need to think about commision charges.
That being said I have not used the pay ahead in anything other then my open account because when you start adding up the amount times several accounts then it is not worth it.