Gigablast same speeds as 300 Mbps package

A few days ago I signed up for Gigablast, this is DOCSIS not fiber.  I bought a new modem, Motorola MB8600, and have yet to see anything close to 1 Gbps.  Today a service technician came out and using his meter direct into the modem tested my connection at about 950 Mbps.  While he was here, I then plugged my laptop directly into the modem and conducted another speed test from the Cox website.  The speed test was right about 300 Mbps connected to my laptop with a 1000 Mbit NIC and a CAT6 cable.  I get the same results once I pass traffic through my router.

The technician told me it was likely my equipment.  This makes no sense to me as the equipment I tested with was a direct connection to the modem.  I had high hopes for a Gbit connection, however this is quite disappointing and seemingly not worth the difference in the bill if I can't get decent results.

I've seen several other posts very similar to this same situation.  What's going on Cox?