PPLIR have significantly less members that AOPA UK around 15% as I recall. AOPA UK is part of IAOPA which a franchise from AOPA USA. They also represent very different areas of GA and is the reason why there is a cross pollination between the two groups.
AOPA is run as a business only in the sense that it run to cover it's operating costs. There are no shareholders and nothing other than staff salary is taken from the business. Everything else is put towards the costs of representation. The AOPA accounts are freely available to members.
They do have assets such as property, but as has been debated in the past, why sell a property that has minimal costs and spend the money and go and get into debt to get another one? Sound like a recent story of the economy. It should also be noted that the property was a result of an AOPA benefactor who wanted the organisation to be able to devote every penny towards representation rather than fancy office space. Part of the building is sublet and the income goes towards the operation of the business.
These arguments will always rage. The fact is you choose who you want to represent on the basis of your interests. I am an LAA, AOPA, PPLIR member and am happy with the different job that each of these does for me.
I suggest that anyone looking for representation chooses accordingly and like myself they may find that they join more than one.