we just bought an HP d145 and after the initial shock (after years of fast quiet laser printing) we've decided to keep it. yes, it's noisy, and slow(er) than the advertised ppm. they never tell you the real ppm anyway. if you want "draft" quality it's high, but otherwise it's 4-5 ppm color 8ppm b/w. all in all it's alot better than paying kinkos $1 per color page. and after running off 600 double sided promotional flyers (front full page text with grayscale 1.5x2.0 in photo of individual and backside 4 lines of contact info in 30pt font) before we got a low ink warning. i have to say that the first copy was as good as the last one and at $22 per ink cartridge (for 600 double sided copies) that sure beats going to the copy place and forking over 10-15 cents per page.
what we bought it for was color copies (read zdnet review which placed cost at 21 cents pp - which again beats kinky's $1 per color copy) and scaning into pdf format. at first we had issues getting adobe acrobat 5 (full version) to load up the scanned docs and HP customer support was useless. i updated the hp software by downloading v 4.3.5 and it looks like it did away with the crappy ReadIris software that was apparently messing with Acrobat. (make sure to uninstall the older version of hp software first). now it scans (from the duplex tray! no more hand feeding document - i love it!) and opens Acrobat (you'll have to customize it to open tiff files in acrobat in the 'customization' panel). my only concern is that the files are large, but i'm so happy that i got it to work that again i had to tell me wife we were keeping it.
the only difference between the d 135 and 145 is that the 145 has the 2 sided printing acc. included and it takes media cards - do care for the card readers, but the 2 sided accessory made it worth the $100 extra. (i think you can add the 2 sided attachment to the d135 if you buy it from HP)
Staples has it for $599 (minus a mail in $100 staples gift card) - i checked it online and no-go but the retail store had it advertised (NYC).
haven't tried the fax yet, but as a copier it works great (again, remember, this is not a super fast office copier).
sorry, can't address your concern about OSX - we're running off 9.2.2 on a pismo 400