It's a tough one, but, there are some good comments in the thread so far.
Have to agree that you need to fully understand the network topology and configuration before you go messing (from end to end). It's a ball ache of a job but the more info you have before you start to alter anything the less likely you are to have issues, and when they do arise (and they will) you'll have a better understand of their cause and how to deal with them.
Once you have a full picture (or at least the best you can get) you may better understand the 'separation of concerns' approach that has lead to the current set-up and equipment used etc.
Some of the more recent setup/configuration could have been borne out of the fact that others also lacked access to the managed switch or other systems and ended up hacking things together.
The current set-up sounds a bit more like an organic set-up that has grown from needs rather than planning and deployment though.
If the network will continue to expand it might be the right time to start thinking about not consolidating compoents, but re-configuring the network to be more resilient and scalable.
A number of small ISP's I have spoken with are now looking to consolidate their networks and reduce IPv4 wastage in their own networks through PPPoE delivered over MLPS/VPLS (akin to http://mum.mikrotik.com/presentations/US13/kirnak.pdf
& http://community.ubnt.com/ubnt/attachme ... 20MPLS.pdf
Whatever you decide to do though, start with the best map you can and don't start without a back-out strategy unless you enjoy unhappy customers.