Testing as small conf bridge - good!
Our small consulting biz uses PIAF (hosted with Lylix), with a primary role as an audio conferencing server. We want wideband audio conferencing, which doesn't seem to be supported currently.
So I set up blue.box at rentpbx about 2 weeks ago and we're using for one of the conference rooms (bridges callers to the conf extension to the blue.box conference bridge).
We have had no more than 5 concurrent callers, but it is working great.
Was previously testing FusionPBX/Freeswitch hosted at Synapse Global, but decided to move to rentpbx so both my PIAF and blue.box servers could be in Seattle area data centers.
I preferred the FusionPBX GUI (seemed more mature, feature rich), but bluebox is fine for our purposes. I set up a couple of extensions and a SIP trunk, all of which worked, but I haven't done any meaningful testing other than the audio conferencing.
I'm a marketing guy, not a tech guy, but architecturally the separation of signalling and media paths that Freeswitch does just makes sense to me, and so far I think the audio conferencing is a lot better than on Asterisk. I also have to rely on the GUI as a marketing guy, and that's where FreePBX kills what I've seen with SipX, Fusion PBX and now Blue.box. Hopefully they'll catch up, or FreePBX will support Freeswitch (thought that's what FreePBX v3 was going to do).
Hope that helps in some way.