I've heard of a discussion (I believe someone said it was on HellHades site) where they covered relationship between relative increase in the stat which scales the damage and relative increase in crit.damage. Something along the lines of "100% crit.damage is equivalent to 100% increase in your ATK".

That covers instant damage (instant in a sense that it's how much damage is dealt when it's dealt) which is crucial in Arena. How about damage along the run, specifically in relation to speed. To put it simply, is going 20% faster or more often equivalent to dealing 20% more damage over a dungeon run? 

The inspiration for this came when I rolled 4 speed rolls on a Cruel weapon. My first instinct was to just throw it on an Arbiter (the girl loves Speed more than an Alabama tweaker), but then I thought , "it is a Cruel set...would a damage dealer benefit from having a lot of speed, and if so, what kind of damage dealer would benefit from it?" Maybe damage dealers with strong Active skills but ok A1s (Seer)? Or Debuffers who also hit hard (Stag Knight)? How about damage dealers with great utility on their skills? Raw damage dealers?

Perfect example is Genzin. The damn thing goes A LOT, his turn meter just keeps filling. His damage is nothing to write home about when he hits, but he does hit a lot. Rotos is another example, although Rotos does hit hard...and he also hits a lot. 

It may require some gearing, but I may test that later. Or if someone has covered it already, feel free to let me know if it's