Hey tuathal, welcome to the team. I'll try to answer your question, but be advised, the general opinions vs. orifices rule is in effect.
Before the point structure was revised and many of the gromacs units were still beta, running the advmethods flag on an SSE enabled machine led to much higher ppd.
It was incorrectly assumed that the advmethods flag = gromacs, when it's actual purpose was to accept beta and early gen workunits. This can still be advantageous because some early units are given bonus points,(the 13xx series currently), of up to ~30%, again resulting in higher ppd yields.
To wrap it up, on a sse capable system, currently shipping units do seem to yield higher ppd when the advmethods flag is used. Please note that current crop of new units also added much higher memory requirements,(Stanford originally listed 250+mb, may have gone up since), you must also set the allow wu over >5mb option.
Even with flags and tweaks, you're still at the mercy of the assignment server, units are assigned based on weighted priority.
Of course you realize that we're all here for the science, so none of this points nonsense makes any difference