It was unfortunate that this happened. The two tools have to be using the same dll versions as they are installed into the same folder. I upgraded to a later build of the janus gridex to check whether an issue I was having was going away, (before I tried out v3 betas) during v2 development, however that was not the case, but rolling back wasn't an option either.
We're still undecided what to do with templatestudio for v2: merge it with the designer or not, ship it with the designer or not.