I used the FX570 for my APTL's
And found it very handy with all the conversions.
I never saw any of the exam halls checking which calculator you are taking in. (Gat and Glasgow)
I presume if you take the piss with a FX7000G or the like you will get caught but lets face it unless the invigilators have any form of technical trade they won't know the difference between different types, unless of course you have a massive graphical screen.
mj