I have played the Halo: Reach Demo, which is basically Long Night of Solace until you get to the part you need to blow the Corvette's engines/thrusters/thingies.
I waited for the first BOB to appear (the one in the area where the Spirits drop enemies indefinitely [not on the Wraith platform]) and this is what I have seen:
The drop pod falls, it opens and after the get-out-of-the-pod animation runs, the BOB instantly disappears - not like he was cloaked, like he didn't even exist, only the getting out animation existed.
Conclusion: BOBs are not regular enemies and are not simply mini-bosses - they serve a purpose, otherwise the BOB wouldn't have disappeared in the Demo.
No pics/video because the Demo doesn't have Theater.