Cix don't appear to offer FTTP. At least it doesn't appear on their website. Having clicked on their "Control Panel" link it does provide a lot of information. I assume that's what you mean, because the way it is presented is very different to AA's

.
As Ian says, the new FTTP infrastructure will make no technical change to FTTC provision. It could though lead to a large percentage of FTTC users in your area with similar speeds upgrading. This would remove them from their connections to the FTTC cabinet which could result in a faster connection for you due to the loss of crosstalk if present.
That would only show up if and when it happened.
Is there any particular reason you have two lines, other than the speed question and the (by the sound of it) high usage your son makes of the throughput capacity? How much data does he actually download? It will show in his Control Panel for ages of history. I'm assuming the 100-200GB you cite is your usage on the Pulse8 line.
I'm wondering whether simply upgrading that line to FTTP and ditch the Pulse 8 one might be your best solution. Possibly keeo their phone service if you want a conventional landline - I have mine from them.
Either at 80 or 160Mbps. The AAISP website seem to say they are the same price from them but it depends on other factors whether they can provide the 160. It's unclear at first glance.
My broadband basic info/help site -
www.robertos.me.uk. Domains, site and mail hosting -
Tsohost.
Connection - AAISP Home::1 80/20. 200GB. Sync 70745/12295Kbps @ 600m. BQMs -
IPv4 &
IPv6
Edited by RobertoS (Wed 29-Aug-18 12:21:04)