The good news on this is that over the transition period we are working to bring all of the current Advisory Services on to the same funding structure for JISC funding. The Company will have a very lightweight Collaboration Agreement with each Service - this will allow for maximum flexibility by just agreeing that the two parties will work together on a range of activities.
This will then be supported by a Service Level Agreement (SLA), which can be altered to take in to account the differences in each service. This can then be extended if new activities come along - or indeed slightly different arrangements can be put in place under the Collaboration Agreement if the SLA approach doesn't not fit a new area of work.
I think this offers plenty of opportunities for flexible models to meet the differing needs of all of the Services without creating any inequality of approach to each Service.