Yes no issue on Be hardware newer or oldest for what i test.
Radeon 7xxx series and R7 250 works but only in fbdev mode because glamor crash when open RadeonSi in mesa, this happen on all BE machine (sam460,X5000,X1000,G5 Quad)
Im pretty sure all the gpus 1.1 pcie compatible will work on G5 Quad Radeon and Nvidia,
the gap on BE is only in software (drivers endianess).
If one day mos will run on Quad im sure will use the radeonhd gpus like on X5000 without issue or even better [ Edited by tlosmx 01.02.2018 - 13:27 ]