I'm using the Git Tower beta and I have to say, it works like a charm. It does everything that GitX does, but provides a better UI for everything.
The only thing I miss from GitX is the ability to discard changes per changed line/block. In Tower, it is possible to stage per changed block though.
 One thing that I forgot to mention is that the developers are very active and responsive, even though it's a closed source project. I made a few suggestions and got replies for each of them within a week. (Compared to Gitbox, Git Tower is built by a whole team of devs.)
Regarding specs of the service offered, it just says: I need more memory or disk!
"As part of our beta service we have one size Node Smart Machine available. In our tests so far, few developers have hit those limits. If you are running out of disk or memory send a message to firstname.lastname@example.org or try running Node on a standard SmartOS Smart Machine."
Notice that even if he was at a keynote, selling to the world Mac OS 9 and new iMacs, he personally used a PC laptop running a version of NeXT/OpenStep and the software that was sold to Sun. They eventually hired the same developers to build Keynote.
I just found a quote from Steve that could be one of my favourites quotes ever:
"I started to realize that maybe Thomas Edison did a lot more to improve the world than Karl Marx and Neem Kairolie Baba put together."