CM1200 and hourly latency spikes

I purchase this modem to refresh my aging CM600 which was having some issues.  After working with my ISP, I have a new tap, and drop to my house.  Everything is clean upstream from the tap and at the modem.  Signals are all near perfect.  I have Netgate router monitoring the WAN connection. I'm not using a LAG.  However, roughly every 60 minutes (+/- 10 minutes) I have a spike in average/max latency that goes from 40ms to 600+ ms.  There are times when the latency spike hits over 10 seconds!  Yes, 10 seconds!!  

Spectrum, my ISP, is pointing to the modem and we have seemingly proved that the modem is not working well with their network. They added one of their Arris modems alongside the CM1200, creating two WAN connections to my Netgate router.  Monitoring both modems from the same router is showing the Arris operating perfectly, with consistent latencies sub 40ms, while the cm1200 consistently has these hourly spikes.  The spikes often correlate to a T4 error on the CM1200 but no such issue on the Arris modem.  The NG is running firmware v1.02,1. I read that the other big 3 ISPs are all running few versions ~2.02.x, 

Has anyone experienced similar issues with the CM1200? Anyone know what was fixed between fw versions 1.02.d and 2.02.x? 

I am utterly frustrated with Ng now. I opened a case with them, but their support was useless. If O can't resolve this I will be buying another brand.