I replaced mine with an LG Blu-ray burner, and it's been perfect for four years now.
I also have the two original Superdrives this unit (a 2009 4,1 Mac Pro) came with when I custom ordered it from Apple, and both have barely been used, and zero use to me. They are both in perfect condition (about as close as brand new as you can get) and if you want one, I'm sure it would be easy enough to ship you one.
The only spec to worry about is to get a SATA drive, but this is very nearly every single optical drive sold today.
You also need to remove the front bezel so the tray will fit through the case's front slots. They are typically a separate piece that just snaps off. Back in the day you had to pay attention because not all drives had removable bezels, but AFAIK in the last several years they all have removable bezels now. Just don't get a weird one-off brand and you should be fine. I'd recommend Pioneer, ASUS, and LG.
If you are getting a blu-ray drive (as opposed to DVD), be aware that almost all brands and models will make a drive seek noise once every few minutes when there is no disc in the tray. This only happens in OS X and not Windows. I believe you can avoid this in one of the following ways:
1. OWC sells the LG BD drive with a Mac-specific firmware that doesn't do this.
2. Keep a disc in the drive.
3. This isn't going to be too helpful, but I vaguely remember something about some setting in OS X. Maybe Spotlight indexing? Or power savings?
I had an external LG BD-R that I was using with my mini.
I repurposed it and swapped it out with the stock Apple "Superdrive" which was also made by LG.
I'm not sure how pertinent this is for OSX, but back in my PC days there was a concern w/riplock. Some drives had hackable firmware (pioneers IIRC) that made the drives run at their advertised speeds all the time. The riplock throttling technology was supposed to discourage optical disc ripping (e.g. ripping CDs to MP3 for upload to Napster...yes, I'm old.)