Me and Marzuku tested our speeds together on skeleton. At the same level (25) With a 4 Agility difference there was less than a 5% increase in speed. Compared to other stats which have an apprx. 20% dif after 5 stat points on average. (these estimates aren't anywhere near to exact, but aren't exaggerateratively high or low) I understand that there would be a dif depending where in the range we were ( a 30-34 stat diff would have a smaller effect than a 20-24 stat dif due to the way stats stack) I was 20 agil he was 24 agil, I consider this to be low agility for meelee classes. so the difference should have been more effective if my perspective is correct.
Maybe agility's value curve is set higher than other stats? I know agility is supposed to be effective for mages and meelee, but neither class has expressed much advantage. If anyone would like to build a character of reversed stats to mine (str and agil reversed) I'll pm you my stats and we'll test dps.