i was pleasantly surprised with the rendering speed of ArtWorks on the A6/VRPC at Wakefield. However, I wouldn't take it as a representative average because the rendering is done by short loops that get executed a lot. JITs such as VRPC handle this well, as does the StrongARM engine in Aemulor; hence the big speed increase from ARM610->SA.
As with any emulator, some operations will be faster, some slower. To me the A6 I tried didn't feel nearly as slick as the Iyonix but unfortunately there wasn't much software on the machine to get a better feel for its speed.