I only ever tried the ECI modem and as I used to get full sync it obviously made no difference.
Perhaps I should have a another look into it, I was actually planning to find those instructions for flashing OpenWRT on the ECI modem so that would seem like a good time to look into it.
I do also have a Home Hub 5 with LEDE installed but apparently the modem driver they use isn't capable of full speed there anyway.
I would be loath to pay for anything else unless it was G.fast compatible so it was a little future proof.
[EDIT]
Tested the Home Hub 5 and I think whoever said its lacking was thinking when using it as a fully router. I tried it in bridge mode and it seemed like it might work, but there is some weird stability issues where traffic would stop flowing properly, plus it doesn't support baby-jumbo frames on the Switch so that's a drag.
Sync wise though it does look like my line has a little leeway with other modems with a gain of nearly 2Mbit, although not close to enough to be worth spending money on.
Status: UP
Line State: showtime_tc_sync [0x801]
Line Mode: G.993.2 (VDSL2)
Annex: B
Profile: 17a
Data Rate: 71.889 Mb/s / 20.000 Mb/s
Max. Attainable Data Rate (ATTNDR): 72.137 Mb/s / 28.506 Mb/s
Latency: 0.0 ms / 0.0 ms
Line Attenuation (LATN): 12.9 dB / 15.5 dB
Signal Attenuation (SATN): 12.9 dB / 15.3 dB
Noise Margin (SNR): 6 dB / 12 dB
Aggregate Transmit Power(ACTATP): 6.2 dB / 13.8 dB
Forward Error Correction Seconds (FECS): 188 / 57278
Errored seconds (ES): 5 / 9888
Severely Errored Seconds (SES): 0 / 2
Loss of Signal Seconds (LOSS): 0 / 0
Unavailable Seconds (UAS): 35 / 35
Header Error Code Errors (HEC): 0 / 0
Non Pre-emtive CRC errors (CRC_P): 3 / 0
Pre-emtive CRC errors (CRCP_P): 0 / 0
Line Uptime: 1h 24m 22s
ATU-C System Vendor ID: Infineon 208.134
Power Management Mode: L0 - Synchronized