>Maybe introducing basic 2D drivers for GCN cards first would be better with respect to users of OS4 on Sam460 or X5000 who would like to try out MorphOS.

Agreed. I sent him one (GCN card) before these new drivers were introduced. Actually two. Specifically a GCN1 dual bios 7850 that could be switched to 7870 mode, and and Gen2 R7 260X. I can't remember if I thought to include a 7750 or 7770, probably not.

Right now, a 2D GCN1 driver for cards like the 7750 would be perfect.
Although I'm sure Mark has had to adjust from the Terascale architecture to GCN, since the development of Terascale was quite linear.

Again, we need to pay our graphics team. Hans isn't working for free.