As a viable dueling concept it's going to be struggling I think. Kind of like Academy if you Extact/Cap/etc.. their Academy. If someone removes your one Earthcraft your kind of stuck. Winning with finite Squirrels could work I guess but isn't exactly quick. May need to pack a Morphling or at least a Living Wish to go get an alternate win condition.
The Sterling Groves seem to be the way to go and they do have synergy with the Squirrelcraft combo obviously and give you another way to tutor for it. Could try Sylvan Library as an alternate, limited search spell, that gains protection with a Grove out. Not sure the 4 Intuitions should stay in as you can only go Earthcraft, Regrowth, Replenish as a way to get it out.
Maybe splashing black for the Demonic and Vampiric would be more consistent? Doesn't open you up for graveyard hate quite as bad as Intuition.. With a Squirrel Nest already out you could easily run Diabolic Intent as well. You could also run Yawgmoth's Will to replay the combo if it gets countered/destroyed. Black gains you sideboard or main Duress as well which is pretty strong against control or the newer aggro/control.
You could include a Gaea's Cradle for some truly abusive X spells once you make enough squirrels. Mind Twist, Stroke, Fireball (always split to a Squirrel to avoid Misdirection), and so on. This works pretty good even if you don't have a million squirrels and gets around Moat's OK.
If you want to stay U/G you could include a Reclaim as an alternate Intuition target: Earthcraft, Regrowth, Reclaim.
I still like it as a multiplayer deck though but only play it when the people you typically play against play combo to

It was much faster with 3 Earthcrafts but with Planar Portal and it being multiplayer (slower) it should still be viable.
I run Bloody Squirrels that really hoses up alot of people's multi-player decks/combos, especially heavy type one combo's that rely on Dual Lands.
It's just a multiplayer deck but it does still uses Squirrels

Bloody Squirrels
Green 25
Birds of Paradise (G RV) 4
Kamal, Fist of Krosa (GG4 - ON) 1
Gigapede(GG3 - ON) - 1
Spellbane Centaur(G2 - OD) - 1
Verdant Force (GGG5 - TM) 1
Wall of Blossoms (G1 SH) - 4
City of Solitude (G2 - VI) 4
Dense Foliage (G2 - WL) - 1
Earthcraft (G1 TM) 1
Squirrel Nest (GG1 OD) 3
Regrowth (G1 RV) 1
Taste of Paradise (G3 AL) - 1
Naturalize (G1 ON) - 1
Vitalize (G WL) - 1
Red 13
Anger (R3 - JG) 1
Goblin Sharpshooter (R2 - ON) 2
Gorilla Shaman (R - AL) - 1
Blood Moon (R2 CH) 4
Fireball(RX RV) - 1
Red Elemental Blast (R RV) - 4
Artifact 4
Altar of Dementia (2 TM) 1
Planar Portal (6 IN) - 1
Soldevi Digger (2 - AL) 1
Tormods Crypt (0 - TD) - 1
Land 24
Forest (MG) - 10
Gaeas Cradle (US) 2
Mountain (MG) - 7
Strip Mine (4th) 1
Wasteland ( TM) 4