Try alternative firmware
I use a Netgear DG834G v2 on a Zen connection and all is fine even though it uses the AR7 chip (the newer v3 uses a different chipset I believe). However, I used to suffer a lot with disconnections caused by fluctuating noise ratios when I was using an earlier version of the firmware, V3.01.25. Since upgrading the firmware to V3.01.31 ten months ago, I have had no more problems.
The problems reported by Zen don't seem to affect lines with stable SNRs so only folk with a) a fluctuating SNR and b) the AR7 chipset would see disconnections. In any event, it is worth experimenting with different firmware versions before declaring the AR7 as the villain.
PS. There isn't a chance in Hell that Zen are trying to shift blame here. They are possibly the most honest and technically proficient ISP in the country.