Hitron Coda56 software/firmware versions and performance on 2 Gig plan

I have been using a Hitron Coda56 modem on my 2 Gb plan for the last 18 months.  So far, I've been very happy with the performance which has been improving as the Next-Gen/Mid-Split provisioning upgrades have rolled out.  I am getting ~2 Gb download and ~ 350 Mb up.  I see my plan says it should be 2 Gb up/down.  I know the Coda56 is supposed to be capable of at least 1 Gb upload, but am not getting this performance.  I contacted the Xfinity app and subsequently engaged a human tech support person who agreed that my modem could have the software/firmware upgraded by Xfinity to get better performance.  My basic specs on the Coda56 are:  Hardware version: 1A; Software version:  7.3.5.3.2b1  I was told the modem should be upgraded to software version V16.03.11.14  I was also told this would be a "backend" upgrade and would take about 3 hours or so.  Does this sound correct?  The new software version number looks much different than the existing version, not just an incremental change in number.  I am wondering if this information is incorrect.  Anyway, I waited overnight and there is no sign of the upgrade.

Separately, I spoke to an Xfinity sales person (in store) about Xfinity vs AT&T fiber service (already in my neighborhood) and was told I could get full 2 Gb up/down with the new Xfinity gateway hardware.  I'd rather use my own modem, even if I have to yield some speed on the upload side.  I just want to understand what the actual limits are for the Coda56 vs the Xfinity gateway.  As well, if I am not getting the full upload speed with the Coda56 would this apply to the Xfinity gateway (that is, is the upload limit a neighborhood service limit or is it the modem/gateway)?

Thanks for any info.