Don't forget that you'll never get the full speed of all the connections on a single download since pfSense works in a round robin fashion balancing between all 8 connections along with what "weights" are set for each interface. Unless the speedtest can make multiple links between servers and aggregate them, the fastest your going to see for speed is one of the 8 connections at a given time.
Now if you were say downloading a torrent or using a download manager, you could see some awesome results
If I remember correctly reading somewhere on the vast internet, "true" load balancing can be achieved with BGP, but that's a whole other cup of tea let alone getting it from Charter without breaking the bank.