Drop the Old API
Maintaining two API is a pain.
The amount of code that we have to support the old API has grown out of hand it it leads to headaches. I propose we drop it entirely and just stick with the new one.
Porting tests written in the old API to the new one should not be a big task and I will take on the task of doing it personally.
Just add a ticket for the plugin you would like to see port it and I will make it run in the new API.