Thank you for the reply, I'll try to provide a little more context to the question.
The teams are cross-functional but largely undifferentiated with no driver to have them differentiate. As a company we provide software development services to a range of clients and are organised into cross-functional teams of 5 - 9 people for simplicity's sake. The rationale at the time was each team would run a little like a business within the business - each responsible for its own gross profit, resource allocation, forecasting of work, etc. This has worked very well to date but we are starting to see shortcomings when it comes to the need for collaboration between teams and, unfortunately, not all work arrives in perfect team-sized chunks. Sometimes a team may be over capacity and others under capacity. We are looking for the next step beyond rigid team boundaries but don't want to return to the days of a single large "resource pool". We can see how Holacracy will afford us better self-determination and greater flexibility but are trying to work out how best to map the current model before moving forward.