I've decided to run a mythic playtest within my Runelords campaign (as if my title didn't give it away :P ).
The party is 6 strong and so far, just from initial observation, here's what we have:
So far, a lot of "dual path" takers, lots of "one archetype + Champion"
Even the Wizard is taking Champion as a 2nd path, to grab the armor-related champion abilities at low tiers before he snags the higher level Archmage stuff.
There are 2 divine casters in the party, a Druid and a Cleric (who's multiclassing into fighter, as he's more of a crossbow-user, Crusader of Abadar. The Druid is taking Heirophant with Marshal as a 2nd path. I believe the Cleric is Champion/Marshal.
Our Paladin is a Guardian/Champion. I believe she only took Champion to snag the "to the death" path ability, which mystifies me as to why it's not on the Guardian path.
The Rogue of the party is a Multiclass character as well, going Trickster for his path. I think he may take another path for his 2nd feat.
My personal observation: Dual Path is really, really good. It's one of those that, unless your going for a particular set of path abilities/feats, it's almost a no-brainer to take. While I understand that not everyone is going to take it, or wants to take it, I personally feel it's one of the most valuable ones to take.
I'll update more here as I have more to post. We'll probably play once or twice a month, and as right now, they just finished the Misgivings, and are Tier 2, about to head to Magnimar.
I am interested! I've just started a group on RotR, and I'm curious to try mythic at low levels. I've dropped a few mythic tiers in my other group's high-level, post-Jade Regent game, but they seem like a different beast at low levels.
Still, I'm hesitant to introduce mythic in RotR right away - the tiers can be more and less powerful than a regular level. When and for what reasons are you granting players Mythic Tiers?