Introducing broker for Transact Futures. Transact is not bad, but their trading platform is pretty old, which you can see and feel. They are one of the smallest FCMs around (together with AMP, Ironbeam...).
You will get better rates if you go directly with Transact. But Infinity will give you a good additional service, I would say they are great for (new) traders that like lots of handholding, traders that need hints for their trading, help with the platform...
If you are such a trader, they might be pretty ok for you.
If you know what you are doing and you need competitive rates, then there are probably better alternatives around.