I have mixed views on the CofE. For primary school kids I have no doubt that it's a massive step in the right direction. The research almost entirely supports that. However, at high school level (particularly Standard Grade +) I'm not convinced that it's such a good idea.
Anyway, to try to keep on topic; I do think the new system will more or less be the same as the old in terms of how many points UCAS suggest each grade is worth (i.e. a 1 at SG will be the same as an A in the new version of SGs, and so on). The more complicated part is comparing grades across borders.
A question that BA should probably look to answer: if BBBB is required then will they accept BBBCC, where the two Cs are considered equal to or better than one B? We see this type of question asked frequently enough in here for it to warrant an answer in their frequently asked questions.