Quote - 2.2 is for Macs. PC monitors are usually "corrected" to 1.8 (I use the quotes because present day LCD/LED monitors are actually capable of linear response but, for comptibility reasons, warped to behave like analogic tubes).

Exactly the other way around, PC 2.2, Mac 1.8 (at least it was).

On the topic: Often one uses Photoshop to do alpha-compositing on the rendered images. Alpha-compositing (with the alpha channel in e.g. PNG-output) is an inherently linear operation, so you normally would have to linearize the images anyway when getting them into Photoshop. So it is probably easier just to render without GC and do it once after the compositing. Unless Photoshop supports image operations of gamma corrected channels, but i do not have Photoshop to check, maybe it does nowadays, in any case it is always best to know what you are doing (and what photoshop is doing :-)