The drive in my 2008 Mac Pro (a Pioneer) is working fine. Who knows? They have to source these probably months before production. That said, I don't think I've ever had a slot-loading optical drive last more than a year in any iMac, Powerbook or MBP. Hate those things.
I've never had a problem with any drive fitting the front cut-out of the Mac Pro case. If you watch the video at OWC, it probably covers removing the perpendicular front plate of the drive tray. It's a pretty-easy snap off. They all seem meant to do this.
I'm not aware of any optical drives that claim Mac compatibility, just like hard drives. They all use standard protocols, as far as I know. The most common issues that seem to come up are drives disappearing when the Mac sleeps, or specific things like that. A reboot will fix it. Or, as I said, check the reports on xlr8yourmac.com. This is where the LG Blu-ray drive beats Pioneer's (and others).
To compare drive models, I'll usually hit newegg.com, since they carry most. Numbers usually indicate progression in features/speed/time. Letters often just indicate color, internal/external, or even simply OEM vs retail versions.