At the moment I play this game on a Pentium SU4100 and its quite ok on lowest settings(on Windows, I will try it with Ubuntu 12.04 again).
So I am wondering, if this would run better on a E-450(on Linux obv). I think it should do so. The gpu should be way better then a Intel GMA.
If not, I will wait til Trinity.
I got a frame-rate varying between 15 and 20 fps at the lowest settings and native display resolution using the mesa drivers. The hardware can definitely do more, so probably the Catalyst driver would not have a problem with it even on higher quality settings, but it's not trivial to test with Catalyst as i have the KMS/DRM drivers built into the kernel. This is my hardware and software configuration as printed by phoronix test suite:
Processor: AMD E-450 APU with Radeon HD @ 1.65GHz (2 Cores), Motherboard: MSI MS-1245, Memory: 3328MB, Disk: 320GB Western Digital WDC WD3200BPVT-2, Graphics: Gallium 0.4 on AMD PALM (200/667MHz)
I tried HoN on Windows as well, just for fun. And the bad news is that it seems to be mostly CPU bound, not GPU. For example, with the OpenGL renderer I got the same 15-20 fps even with lowest details. But increasing the detail level to the maximum did not affect the frame rate with a significant amount while indeed providing a much better looking image. With the DirectX renderer changing the detail did make a difference, the frame-rate varied around 30 fps on high levels of details and around 50 fps on low levels while there where few stationary units on the screen. However, when a battle was taking place the frame-rate even with DirectX on low settings dropped from 50 fps to 20 or even less.
So, at least for this game, probably Intel CPUs are better suited, as they have better single-threaded performance and the GPU doesn't seem to count that much anyway.