if you need latency data, and that being for data as well as round trip for internal processing time as well as round trip of your order from server through brokerage, off to trading venue/ECN/exchange and back, your broker or most savvy brokers would be HAPPY to provide that. If not, or the old "well, I'm not sure, but it's LIGHTNING FAST!" It's probably not a broker you would actually need.
You can get this data quite easily by contacting the brokers. If they're good, they'll have it or be happy to provide/test for you.
You can get this data quite easily by contacting the brokers. If they're good, they'll have it or be happy to provide/test for you.