UA has cut premium capacity on this route by 50%. First they replaced 777s with 767s, then the new seats - 11 1st class seats are now 5, and 49 business are now 28. All my recent flights have been full, even in typically slow months when previously I almost had the cabin to myself at times!
UA now has a competitive product - BA still serves dinner in their lounge prior to takeoff, but is otherwise no better than new UA.
Interestingly UA have doubled the price of B fares on that route - it would be interesting to know how many of those fail to get upgraded, but I would guess UA is now getting good revenue for almost every C seat.
Although UA taxes come to $156 in coach, the BA equivalent is $440! Also, if you do upgrade, you still just pay the coach taxes.
You could never get Z fares for $600 - cheapest I have ever seen is around $3,000 return.
I am looking forward to UA putting more capacity on the route - cheaper prices would be nice, but I hate getting a choice of a handful of poor seats when I book, and pay for, a C/D seat a week in advance.