I'm a mac user also.
I adore my PRS-505, read classic and popular fiction mostly.
I have no need for wireless connectivity, touch screen, downloading today's NY Times, or whatever.
Calibre is fantastic for Mac users; clear, simple, works every time for me. I never connected my PRS to a PC; don't have to. It charges on my Mac, shows up on the desktop, and with Calibre I can load/convert any .txt, .html, .rtf, and some PDFs (depending on what's in it) perfectly.
I've used the Kindle; I find it a little bulky, poorly designed, and cheap-feeling. I have no need for the keyboard; I read with my eyes
.
I don't like the Sony 700; the screen is vastly inferior to the 505 in my opinion, I think a touch-screen is totally ridiculous to read a book (I hold my reader in 1 hand, change the page with a finger/thumb on that hand, my other had is happy not having to do anything, thank you) and it gets fingerprints everywhere.
I use a $25 head-lamp from Brookstone to read at night; it is way superior to the Sony add-on light for the 505 or the 700's built-in light. So I look like a nerd; no one sees me at home in the dark. The head-lamp works better than anything else, and adds no weight, battery drain, and I can use it in any position.
MY DISCLAIMER:
I don't buy ebooks, I find what I need on the net. Some legally, some not. I do this with many things, and I have the knowledge and ability to put whatever I find into a format my reader understands- and make it look perfect - with little effort. If you are the type that finds this offensive, I'm sorry; I'm just here to help a fellow mac user (it downright hurts me to see Mac users get P.Oed because they can't use Sony's store.) There's a whole lot you can do without it, and it never stopped me from using my reader every night with any book I want to load into it.
By the way, the battery lasts a VERY long time; I read at least 12-15 hrs. a week and the battery level MAY go down 1 notch (out of 4). The page turn is fine; I press it on the beginning of the last line of text, and by the time I finish that line it changes pages. Perfect.
I don't know anyone who needs more than 3 Font sizes; I usually read on 'S', sometimes 'M' (depending on how I formatted the book in the first place), and the 'L' is, to me, for the truly visually impaired (which thankfully I am not).
I hope I helped and didn't offend.