SQL has zero problems failing over VLDB's and I can contest to that since I have 2 node clusters that fail over 1,380 databases ranging from 100GB to 1.5TB without a problem. Just like everyone else has said this isn't a SQL thing since files are not copied; the volumes are shared.

As for the SAN I can see this being a problem with their replication service over WAN but again it wouldn't be a file size problem but more of a LUN size problem since the replication on the SAN is done at the bit level.

We use EqualLogic and DELL switches and we replicate 9TB without a hitch so i'm guessing their talking about geo-replication over WAN or something.

my 3 cents

-King