I bought a Thalia and a G7th Performance 2 to see which I preferred, if either. I'm using a 322e and a GS-mini Koa. I only play sitting down with no strap. They both work fine, and are easy to attach and reposition with my fretting hand. I'm not SURE if intonation is improved with either, but believe that it is better than the others I have tried.
Functionally they seem about the same to me, but the G7th is MUCH lighter and thinner, getting in the way of my fretting less. (If we weren't using 1st position chords we wouldn't need a capo, right?)
Since it is about half the price, I would suggest you try the G7th first, however, in my opinion, the Thalia is a fine option. It is awfully pretty... and, I don't yet know how well the clutch on the G7th will hold up.