Standardised Higher-Layer CAN or invent my own?

CANOpen and MicroCANOpen are 2 higher-layer CAN protocols, however, they might be a slight overkill for this project, this needs to be investigated quite a bit probably.
Known advantages:
+With CANOpen, there is a number of tools already supporting the higher-layered protocol
+Can be customised and optimised
Likley disadvantages:
+Probably steep learning curve, though, probably just as much as implementing own drivers etc...
+Probably take up a large amount of memory, though, hopefully could be optimised.