I received some figures from Claymore Castings yesterday. Here's how they look beside some Crann Tara and Front Rank.
From left to right: Crann Tara, Crann Tara, Claymore Castings, Front Rank.
You can see that Crann Tara are a bit slender compared to the others and that Claymore Castings are quite stocky compared to Crann Tara. Front Rank are a bit in between, at least on these samples.
I would have no difficult using these ranges in the same army but probably best in their own units. They all paint up nicely.
Crann Tara don't do Prussians at the moment, Claymore Castings only do Prussians at the moment and Front Rank do everyone.