I've been playing FFXIV via the Mac client since it was originally released. I got the email about the refund, but I decided to forego it and keep playing. I just love this game too darn much.

For the record, specs:
MacBook Air (13-inch, Mid 2013)
Processor: 1.7 GHz Intel Core i7
Memory: 8GB 1600 MHz DDR3
Graphics: Intel HD Graphics 5000 1536 MB

I've been running it full screen since I started. Frame rate has been generally pretty bad, but it's gotten better and now floats around 15 fps most of the time. Sometimes I get spikes, but my best sustained rate is around 20 fps.

We also have a new Mac mini that plays it at 1080p admirably (20-25 fps).