Although you didn't mention the cable modem model, I assume it is the Netgear Model:CM1150V-100NAS, since, as an owner, I got an email regarding your question. First and foremost, the CN1150V is only a cable modem, while the 1900 (there appear to be several versions) is a modem/router combination. Also, while I can't go into specifics of each 1900 models' capabilities, some appear to offer voice capability while others don't. The 1150V does offer VIOP connections. The other big difference appears to be that the 1900's only come in DICSIS 3.0 versions, 10x slower than 3.1 (according to their specs).
Personally, I've only had my setup for a few weeks, so I have no long term experience to share. My 1150V is paired to the new Nighthawk Model:RAX80-100NAS. At this point my opinion of these models is disappointment. Every day it seems I lose my connection have to troubleshoot and manually reboot them. Today it took 30 minutes to reconnect. My old Arris modem and Netgear 1600 router seldom had any problems.
I only mention this because having 2 components to troubleshoot may be a factor in deciding on a modem/router combination. Also, while the difference in speed may be a factor for you, I cannot yet take advantage of the higher speeds DOCSIS 3.1 offers. I chose my setup primarily for the WiFi capability of the RAX80 that wasn't available in the combo units. The 1150V seemed to be a good match for it. Now if only they were reliable.