To be honest, we have no issues with CaaS module version 2
Version 3 however does not have customizable json channel, it has pre-defined methods which can create json output.
From personal opinion, i find that CaaS module version 3 is a good approach when creating a new project from scratch as one can adapt the development according to the 'un-customizable json' from the beginning... but for projects which run CaaS modules from years it could be a problem that the json data cannot be handled as required. 🙂