With all the talk of the cost savings implemented by BA, I am struggling to see how this is one of them. Entering a third party lounge on a pay per customer basis I assume will be far more expensive for BA than running their own ship with their own products. Not to mention the rent and other associated costs that they will be paying out for the new development while it is being built.
The champagne situation (or lack of it) could have been handled better, and surely a better solution should have been sought for F passengers and GCH's. I wouldn't imagine any of the products in there are brought in from BA, and the champagne purchased on deals that were with the £8 per glass sale price in mind. In their own lounges they could readily afford to give it away one would think with the buying power of such a large institution.
My overall opinion is that the deal (certainly for F & GCH's) should be slightly nearer the former offering where the bar is concerned, but now it's struck I can't personally see it changing. I have yet to use the facilities since BA are using but in the past I've always found it to be very comparable to the Terraces before one had access to such.