Check out the Sandisk Image Mate All In One - connects via USB3 and reads SDHC, SDXC, MMC, Compact Flash, MS, Pro, Duo, ProDuo, and Micro SDHC, Micro SDXC. We use this and it works great with all media we've tried, including Canon uncompressed 10 bit 422 fed to a BMD video assist recording to a Sandisk Extreme Pro card.
The transfer speed will depend on the spec of the cards you are using. We seldom shoot with go pros so I can't answer that precisely. We mostly use Sony SxS cards, P2 cards and SDXC cards. We bought this mainly for the compact flash reading ability, and with Sandisk Extreme Pro 160MB/s cards it is very fast.
We are using the Lexar Professional workflow. If you have more then one card to offload at a time and a fast hard drive to offload to, it's very fast! You can offload up to 4 cards with a single tower (you can link more than one tower via Thunderbolt). You can choose from many card readers so the same tower can offload different cards models.
We use this with Shotputpro to get a checksum. Works great !