Just did Turn 4 last night, which completely changed my opinion.

If higher weapon damage increases Flash aggro, which I believe it does and Valk's pre-release data pointed towards, then Curtana +1 1st upgrade. Save the myths for it even if you haven't downed Titan yet.

That fight is literally you flashing 75% of the fight and riot blading the other 25% for mana. Not to mention the Soldiers that are immune to physical attacks so the only way to build aggro on them is with Flash. It's also a constant dps race, so there is no dps slowing down so that you can build a lead. I don't care if the +1 was only a small increase, I want every increase on that fight that I can get to help with aggro management and mana efficiency.

It's also a blast!