Is there any downside to running uNSLUng 5.5
I personally think it is a better firmware than 6.8.
However do remember that there is no support for NTFS drives however.
All of mine are natively formatted ext3 on the slugs.
I have 2 slugs, my main one running mt-daapd 024 (unslung 5.5) and another test one (unslung 6.8.) I do have an experimental firefly (1157 I think ) installed, and it seems to be stable enough.
Both the slugs are de-underclocked, but I do feel that the unslung 5.5 version is just slightly quicker. I noticed during the unslinging of 6.8 that the unslung 6.8 firmware uses about 97% of the flash mem compared to about 83% in 5.5.
I am waiting for the first stable release of firefly before I ungrade my unslung v5.5 slug. After which I will probably reflash my 6.8 down to 5.5 as well.