I have both the Ruby and the Abyss. The Ruby is my primary, right post, reg and the Abyss is my alternate, left post, reg. I like them both and would reccomend either one to someone looking to buy a new reg. They both breath excellent at any depth. I too got my Ruby cheap, I was working at a LDS when I bought it so it was deffinately below market price.
The only concern I would have with the TI modle is the fact that TI is not recommended for use with high contractions of O2 so it may not be recommended for Nitrox. I don't know for sure what Mares has to say about this or even if the first stage is solid TI or just plated and if the inside of the first stage is TI plated or chrome plated. Might be worth looking into though.
Scott