Yes I absolutely still work on fifo, actually 0.7.0 is around the corner right now and gets polished for release.

To the second question, I'll answer that from a 'out of the box' perspective so things go not off the rails because 'when doing X/Y then you can also ...' because as you pointed out both are now open source systems and with enough effort you can make them do everything. Obviously I am a bit biased here, if only for the reason that I know a lot more about FiFo then SDC but I'll try to be as objective as I can. That said I'd really would like to hear what someone with lots of experience with SDC and a bit of FiFo experience thoughts on this are.

The first difference to me is the heritage, while today both are open source, FiFo was born as a open source / community project and has taken this path from the first day. SDC is an commercial product that was then open sourced, which as Bryan pointed out in one of his talks is something really really complicated.

The second point for me, and perhaps the biggest one, is resilience. FiFo is build on the cloud premises of 'everything will fail', systems are redundant, it is master less, leverages CRDT's to mitigate the eventual consistent data model it uses. And that is something that wasn't added to FiFo but was part of it's design from the start (when you heard my talk on the EUC you might remember not always successfully ;). SDC uses a more traditional design, it was build to run on a single server and now Joyent is adding failover and replication to it. (I won't vouch for the correctness of this since it is hard to say what the design was like pre open source but it looks like this is the case from the outside).

The third advantage I see is that with fifo you can start with as little as 3GB as memory in a zone on your system then grow that system as you grow. You have to chose a sensible number of v-nodes but pretty much going from 1 to 3 to 5 servers isn't a issue and thanks to the great work Basho did on riak_core as simple as a single command. SDC comes with a own dedicated server as deployment which makes it rather resource intensive on that front. (I don't count the COOL images that run in a VM here).

Fourth, FiFo runs on vanilla SmartOS, you can not use it one day, decide you want to give it a try and it will just pick up on your setup, and then toss it away the next day and everything keeps running as if nothing ever happened. SDC has special platform images and at least in the past it wasn't as simple as not running the head node to get rid of SDC.

Tachyon, which will have it's full premier with 0.7.0 but is already available as a separate package. Developed together with Lucera it is a monitoring system for servers. Based on kstat to collect metrics and a special metric database to handle the load it can handle second level resolutions for decent installations. So that gives you historic usage and performance metrics on every server and every zone in your system, which is I think unparalleled at the moment at least at this resolution.

What we do with backups and in result the option of cold migration of VM's (kudos to the LeoFS folks at that point) is something new which can be quite interesting for some people.

Last but not least we have a dog as a mascot, which is just so much better ;).