Should I use exFAT or HFS+ on an external HDD for Mac?

I just bought a new WD Elements 2TB HDD to store a good amount of data that my colleague handed me.  The decision is what filesystem do I want to use for the drive.  The only two realistic options for me are HFS+ and exFAT.  I'm an exclusive Mac user but my colleagues also use Linux and Windows, that's why I added exFAT to the list.  I, however, don't plan to share the usage of drive with anyone else.

At first glance, either format would do.  So I decided to try both and just see what the drive looks like when mounted on my computer.  After formatting it as HFS+, the formatted drive showed 2TB of free space but also 852.2 MB of used space!  I thought to myself, what does a spanking new empty HDD do with 852 MB of space?  Not entirely pleased, I tried exFAT next, and it mounted as expected.  I checked again, and the space used was 3MB!  I thought awesome, exFAT it is.  But I figured that I better do one more test before starting to copy hundreds of GB of data.  I created a simple text document that contains less 1K of data and saved it onto the drive.  The size of the document after being saved?  131KB in exFAT!  131 KB for one letter text document!  I couldn't believe my eyes.  I knew that the same document on HFS+ volume would be just 4KB.  Given the large number of small documents I have, that 852.2 MB advantage exFAT has over HFS+ will be eaten up in no time.  So that settled it, the drive will be formated in HFS+ (case sensitive and journaled of course).

For those of you who are also deciding between these two formats, an additional consideration is that exFAT does not support Unix style permissions.  The only option I saw for exFAT was I could "read and write".  This might be problem if you like to preserve the file permission when backing up (i.e. via rsync).  I don't know how Time Machine would function in this circumstance, since I didn't try it.