Hi Trend

My experience of flying CX in Y when I was OWE/BA Gold was excellent. As a OWE you should be able to request an exit row for free in Y. When I last travelled HKG-SUB-HKG, on both occasions the aircraft was swapped to a 3 class plane. On the outward segment I was offered a HK$500 upgrade from Y to Y+ which I snapped up. The cabin was fairly quiet on the outbound with only two other pax.

On the return when I checked in at SUB, I was treated exceptionally well by the check in staff and as said, again the plane had been substituted to a 3 class bird. I was upgraded free of charge on this flight and the cabin was a bit busier this time.

I doubt very much that CX will just give you a Y+ seat if Y is not overbooked or capacity is required due to a 3 class plane substitution.
Best plan of action is to make sure your OW status is in your booking and you check in online at t-48 on the dot. I think from experience on this forum that the lower (ie. BN1) your sequence number and higher status gives you a better chance, although no guarantee, of upgrade when ops require.
Again, this may also depend on how the flight is marketed and if they sell it as a three class service, in which case Y+ may be sold out.

And as someone else may come along and state, if you want to fly in a higher cabin then pay for it to begin with, although I always go along with the thought that I get what I pay for and if I get anything better then bonus

Do come back and let us know how you get on.

Best of luck

Happy & Safe travels

S