I don't currently trade FX, but I traded it alot from early 2004 - late 2005. GFT is the only broker/dealer I ever used, and had absolutely zero complaints as a self-directed trader. There were no phantom price fills I questioned, and pre-econ report strangles were filled on the stops. That part may have changed due to recent limitations on news trading tactics in FX, don't know. If I were trading spot FX again, GFT would be my first choice due to positive experience before.
If it's an intel-Mac, it really doesnt matter..... Use Parallels in Coherence Mode and you're all set.
Just in case anyone is thinking of joining Marketiva they spam relentlessly on ET and other boards. Hard to imagine they are bona fide.