I found a GF2MX card and it does not seem to support polygon smoothing.
bwkaz - front to back does seem strange. It works because of the alpha term in the GL_SRC_ALPHA_SATURATE blend function.
(f, f, f, 1); where f = min(As, 1-Ad)
This mode uses the alpha channel to accumulate the coverage value for each pixel. The other functions work in simple cases but fail where 2 or more smoothed edges overlap.
As for the poor visual performance of the test program, it might be bad because of some default value that needs tweeked. For example I did not set the smooth hint to GL_NICEST -- though setting it does not help.