Looking for a bracket/adapter/caddy for installing a HDD/SSD where the MacBook Pro SuperDrive used to be.
There are two general types:
1) Minimalist open-type brackets (in the truest sense of the word):

- Seems to allow airflow around the SSD/HDD, necessary?
- Will it hold the drive firmly enough?
- The OWC brand that I've seen is expensive. Are there cheaper alternatives to it? (Could not find.)
2) Space-filling caddies that mimic the SuperDrive's shape:

- Are these heavier?
- Do they ompede ventilation around the SSD/HDD and promote overheating?
- This is how the iFixit and MCE OptiBay enclosures look like, as well as the cheaper ones on eBay.
What are their advantages/disadvantages? I have no experience with either.
What are important things to look out for when choosing a bracket?
I also know that the SuperDrive is fixed in place on the unibody enclosure at a lot of points — I wouldn't want to get a caddy that attaches with less. How can I ensure that with either type?