I started testing tonight, and there are some bizarrely predictable problems that I didn't consider:
*3 grove instead of 1 USea and 2 fetches are really... punishing. I realized I had only 13 instead of 16 blue mana, and it came down to bite me a few times.
*With 4 orchards as part of my manabase, it's really common to have 2-4 tokens applying pressure against me, and what have I just done? Increased the planeswalkers count :|
With those changes I improved a little the matchup against shops (which was already good for me), and the others got worse. I think maybe even the control matchups.
As always, there were a few times I casted inferno titan, where I wouldn't be able to cast griselbrand. The only time I missed the oath activation for grisel was against storm, the other matches I would rather have it activated on inferno titan, or at least it would win or still lose the game anyways. I will still make that change (grisel for the 3rd titan), and the others I will have to try better later.
About the walkers: I ended up trying +1 chandra main e +1 Xenagos sideboard. I think Xenagos can help you when you are getting pressured and won't just die to 2 or 3 tokens that were generated along the way, also it has a nice clock and can be though to beat in some situations. Chandra just wins when it ults, but it's +1 will usually just be a 2 damage spell, as it can grab lots of lands, counters, or cards that are too expensive to be cast at that time. It's kinda fast to ult (3 turns after it was cast), but I think it's not enough to deserve a spot. Arlinn is good both as value and to increase the power of oath. It's not as good for value as Xenagos, as Xenagos can make tokens every turn and is good at killing PWs since the tokens also have haste. That being said, I think Xenagos is too much on the "good when not comboing" side of the things, so I think it wouldn't be really good mainboard, maybe sideboard (when we are more ok about not comboing off). And as for Chandra, I don't think I will try her in this shell anymore.
It was still only 1 league, but it was enough to see the biggest mistakes (I guess).
At tomorrow's challenge I will try the original with +1 slice and dice(main) +1 inferno titan +1 sol ring -1 griselbrand -1 ponder -1 mox pearl, and sideboard -1 slice and dice (brought it to main) +1 Xenagos.