So a few thoughts as you're curious about competitive play with this build:
1) Stubborn Denial in the SB? Your only source of blue is Mana Confluence... drop these for something else in that spot.
2) You're currently sitting in the limbo that is straddling the line between aggro and mid-range strategies. You really do have to commit to one or the other if you want to be successful in competitive play. For instance, you're sitting on aggro cards like Bloodsoaked Champion (I am aware of his synergy with Butcher of the Horde for mid-range play), Frenzied Goblin, and Act of Treason; yet, then you have mid-range stuff like Nyx-Fleece Ram, Purphoros, God of the Forge, Sarkhan, the Dragonspeaker and Elspeth. If you want to go with a token build, go that route, but that's a more mid-rangey type strategy. My point is that you really need to pick one or the other and focus more on that specific strategy, cutting out all unnecessary elements for the sake of consistency and redundancy.
3) As for the life loss from Thoughtseize and the various other lands, you have Sorin as a source of life-gain AND need to consider that many other decks are running similarly painful manabases. As a result, I wouldn't stress the life too much but would definitely consider copies of Whip of Erebos for the sideboard.
4) I think you need some amount of the removal suite currently in the SB in the mainboard, regardless of which strategy you opt to follow. In aggro you need stuff to clear the way, in mid-range you have to be able to stabilize the board and deal with opposing threats. Even if you're wanting to do a token-centric Puphoros build, Mardu Charm belongs in the main deck as all three options are welcome.
If you want some potential builds to work from, see this post where I provided aggro and mid-range lists that you could use as a starting point: https://deckbox.org/forum/viewtopic.php?id=22435
I hope some of this helps and I'll happily answer any questions you have.