I don't know anything about Chimera, and not much about Bright, so I'm not commenting on the original post, but the topic of choosing where to trade.
I still think that most traders give too much weight to commissions. Yes, commissions are important, and if you trade a lot of shares, they are probably the most important cost to control. But when deciding where to trade, there are so many other things to consider.
The topic of how often you have access to your money has come up, and to some that's a big deal and it goes into the mix.
There's a wide range of software platforms out there, some more suited to certain styles than others. Software that's poorly suited to your style of trading might cost you more in slippage and missed trades than you save in commissions. Not to mention the up time of the system and data integrity.
There's an even wider range of api capabilities if you have automated strategies.
Not everyone offers the same leverage, and some control how or what you trade. If you get shut out of one trade because you're out of buying power, or your quotes are lagging, you might lose the whole month's commission savings right there.
And don't ignore the importance of trade support. If you lose your internet connection and have a live order in the market, how quickly can you get a hold of someone to cancel it for you? If you get screwed on a bad print from an ecn, who's calling the exchange to go to bat for you?
It's a business of dollars and cents, but don't be penny wise, pound foolish.
