Mhhm, because actually using the Gue'Vessa rules is no longer legal - it was Chapter Approved, which no longer counts for anything. You can't even have Gue'Vessa in a Tau army.
But yeah, if you make an IG army, concentrating mainly on infantry, give them upgrades that make them more elite, have things like Kasrkin in large numbers, and do things like replace shoulder pads with Tau ones (which you can probably buy on ebay...), no one will mind I'm sure. Better check with your local GW though, in case.
Just steer clear of Commissars, Psykers, or large numbers of tanks. A Gue'Vessa army is more likely to be almost purely infantry, as it is rare for Tau to willingly allow the low-tech-level Imperial tanks in to their armies.