Funny thing about full shaman teams with ToW.

Tow alone provides 15% hit and crit.

Then you have 6% crit from Call of Thunder 5/5
Along with 5% crit from Tidal Mastery 5/5 (this is for bolt and chain only, well... and heals)

So 26% crit from Talents.

1 Druid +4 Shamans will for the Shamans have 2% extra crit but 3% less hit, the Druid will have 12% ToW, 5% moonkin, 4% talents, for a total of 21%

Overview (counting talent totals only, not including base stats nor +int/crit rating gear)

Druid + 4 Shamans:
Druid: 21% crit 12% hit (add 4% hit with Balance of Power 2) (Wrath and Starfire) Moonfire will be 27% crit 12% hit (add 4% hit with Balance of Power 2)
Shamans: 28% Crit 12% hit (add 6% hit with Elemental Precision 3, or 3% with Natures Guidance)

5 Shamans:
Shamans: 26% Crit 15% hit (add 6% hit with Elemental Precision 3, or 3% with Natures Guidance)



/edited to remove wrong information.