rpcs3 on OS X

Then the core vs legacy issue: will rpcs3 rely on those deprecated features in the future or will you switch to core only?
What do you think?

For the forseeable future we will still use a compatibility profile and use "deprecated features". Just because some of these features correspond 1:1 to Commands in libGcm. Re-building these features with a GL core features would sometimes involve quite a bit of work.

But if you're up to the task of accurately emulating the deprecated functionality with shaders and reliably sync the additional state with the used shaders then I would suggest adding that as a second renderer option.