Based on the math done

at Tankspot, one can see that every parry is another .24 of an auto-attack due to parry haste. Since both avoids and auto-attacks have a 100% chance to proc SoB assuming a 3.6 speed melee weapon because SoB is a PPM effect to combat people trying to DW tank with faster stuff, that means each point of parry is 1.24 times as good at generating SoB procs as a point in dodge, discounting the diminishing returns of course.

I believe that means that to get the ideal ratio between parry and dodge for SoB purposes you'd need to modify the usual macro or equation that would normally just show the ideal ratio between parry and dodge for maximum avoidance. Exactly how that's done is something I've shot Theck a PM about and will edit in to this post once I receive a reply unless someone else beats me to the punch.

Assuming the parry:dodge ratio is raised to account for more SoB procs, one might then want to compare the damage gained from more RP and auto-attacks with the higher parry versus the likely increased uptime of Riposte if one were to ignore SoB and simply focus on getting the most avoidance out of the least rating. That question isn't so easily answered with pure math and simulations, but my gut would say that going for more parry to get more SoB procs would probably be better if indeed there is a significant difference at all.

On another note, something I've noticed while browsing through WoL logs is they will tend to show Scent of Blood procs in the Buffs section will be lower than one would expect based on the RP gained in the Power Gains section. As best I can tell this is due to SoB actually having two buffs: One which boosts the next Death Strike, and one which grants the RP. The one that buffs DS is shown in the Buffs section, which means that if you're sitting on 5 stacks and you get another SoB proc then it won't show up there since you're capped but the RP gains will still show up normally.

Edit: So much for an easy way to figure out the best SoB setup. Theck mentioned that would require adding up the SoB procs from both auto-attacks and avoids and then taking the derivative of that sum to get the final ratio. Avoids aren't so hard since they're just based on the enemy's swing rate and your avoidance. Auto-attacks, however, are complicated by parry haste which is based on our parry and the boss's swing plus our own weapon's swing timer. At least boss parry haste is no longer a problem.

However, the interaction between parry and more hits is strong enough (each parry is an extra .24 of a swing after all) that the minimal avoidance lost by not using the ideal parry:dodge ratio is probably not going to be noticed compared to the extra SoB and attacks gained from more dodge. In short, parry>dodge.