Still on Zen 330/50 after one year. I am quite close to the cabinet, so I get full sync. The stability is quite good from the G.fast technology and it can often go weeks without disconnects.
Zen's service itself hasn't really given me any issues, except when I was initially routed via Manchester as opposed to London (as the former was further away). When this was changed, the latency was reduced to expected levels and single-thread speeds were much better. Their support seems competent, but if I recall correctly they sent out an Openreach engineer for the single-thread issues (which were essentially fixed by changing the routing) - but on the plus, the engineer did actually pick up on a few issues that the original installing engineer did not and managed to improve the connection a bit.
I am not using their own hardware so I cannot comment on how good it is. Instead, I've opted for a Zyxel XMG3927-B50A which serves me well as a modem-router combo.
I would say I am happy with the service provided, even if it is a little steep in price. I would say that the product looked appealing with a 12 months contract. Now it looks like they've decided to change it to 18 months so if I want to downgrade to 160/30 then I may just move back to
Pulse8 again to take a 1 month rolling contract (but I want IPv6, which Pulse8 did not offer when I last checked).