The $27 price is for a dual core chip, not a 16 core one. If Avoton prices are anything to go by then expect higher core count chips to be considerably more expensive. Intel is always careful to make sure Atom products don't cannibalize their higher margin Core CPUs so don't expect these to ever be a win from a CPU perf-per-dollar standpoint.
Intel Atoms are utterly useless for that. I'd wager they are useless for most anything that isn't memcpy-bound, so I wonder what makes them put 16 of them into one package.
For memory-bound apps are they sort of useful? For instance, A packet forwarding system that reads a packet, does 3 main-memory lookups, then forwards or drops?
Hard to compare against the Cavium Octeon. x86 general purpose vs MIPS64 with dedicated offload hardware...really depends on the use-case. I have an ERLite and AFAICT it competes with stuff way above it price-wise, e.g. https://store.netgate.com/ADI/RCC-VE-2440-board.aspx
I'd rather run PFSense, but it's not worth an extra $200+ for just my home use.
I would love to see some Blender render benchmark running on it.