Nothing has changed in this modern day iteration.
My Dale Solomonson Advanced 200/70 also had a touch of concave in it. My thanks to the extraordinarily affable Neumatics-R-Us for reminding me that I should indeed have mentioned this mat too.
The other well known Australian designed mat that has a concave is of course the Krypt MT5 and MT has mentioned that the original Surfoplane had, to some degree, inspired this design feature.
Interestingly Surfoplanes are also wedge shape too which PG has also been experimenting with lately.
Even more interesting though, is that PG has started making asymmetrical mats, with this particular one being half 5GF and half XL. This now providing us with the reason for his recent survey enquiring whether or not we only like to go frontside or backside as that is what you are going to have to decide if you want one of these. If you look carefully, you can see that the crease on the left (5GF) is not as deep as the one on the right (XL) and that the mat definitely looks lopsided with all the volume on the right. Very, very interesting times in the mat riding world!