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.
I've worked with Infinity on and off for 11 years. They are solid and do what they say they are going to do. Would they be my go-to futures brokerage? Probably not. There have been more consistent supporters of this site like AMP, NinjaTrader Brokerage, GFF Brokers, and Optimus Futures that I would recommend before Infinity.
Thank you for the kind words Baron! Here is a guide for the OP for Sierra that he can use a reference. SierraChart Guide Specifically, the key to Sierra is hooking it up with a stable data feed for execution. We can connect it to Rithmic, CTS, and CQG data.