Well im mostly playing this deck against a friend who plays really fast landfall deck so judging if im fast enough or not is kinda difficult (last game he hammered me for 18 life in single attack at T5 ... thankfully i was at 25 at the time :) and one turn from victory )

but most of the time, if im not severely unlucky on card draw i should have 4 mana out at t4 (another game - T4 Bloodbond Vampire out at 4/4, next turn its 5/5 through Emissary, and he scooped when i played second Bloodbond making first one 6/6 swinging at T6 with another fresh 4/4 right next to her :) )

the fact that you play against landfall explains a lot :p, and from what you say I can conclude that you'll probably be fine with 22 lands. I seem to have worse luck with lands than you do :D

March from the Tomb over Allied Reinforcements?

March from the Tomb is 5 mana spell (so most probably T7 as earliest) that requires to already have creatures in graveyard. Allied Reinforcements is T4-5 spell that has no other requirements.

im currently thinking about dropping this 2 cards slot for either 2 x Ayli, Eternal Pilgrim or going back to cheaper Oath of Gideon

I've been playtesting with allies recently and I took some notes from your build, and to be honest it's pretty legit except for Ayli she dosen't trigger anything when she hits the field and the only sac outlet for her are herself and the tokens from gideon which is pretty situational, because almost every other creature is something that has a role to play

SHe is there for 2 reasons : 1. she is 2/3 deathtouch that at +10 life turns into targetted removal - basically best 2 drop creature for lifegain deck

1. she is there to capitalize on creatures you will inevitably lose - if you have her on board she either eats the biggest creature or targetted removal that would otherwise target something more important, and when enemy targets something more important or when you are forced to chumpblock, you sick the doomed creature to Aili and gain life from it

if you have reservations, just replace her with something - i would use either 2 more Drana, Liberator of Malakir if you can afford her or Lantern Scout