There's nothing wrong with your G1, it is still great. I have the G2.2 and love it but it is a significant investment, and I really can't say how much better it is. One would expect at least some improvement hard to say if it is worth the cost.
I think if your G1 still runs smooth and feels snappy when navigating your music library, and if there aren't a bunch of new features that you feel you are missing out on, then maybe just stick with it? Or if you can find a dealer to let you try out a G2.2 that would be ideal, compare them directly and see.
I personally didn't like the Altaire series nearly as much as the Aries paired with a nice external DAC.