That sounds like a reasonable step.  Getting IPv6 support would be a big
deal to me, almost as important as a FUSE-based client :-)

I am a bit worried about the dependence on ordering and DNS.  I wonder
if you can instead:

  the SCM is configured with a list of {serverid, server address}, where
  serverid is maybe uint16_t generation, unit16_t serverid.

  there is a new SCM rpc to fetch this, and clients do the fetch

  then we use serverid in the address field.

This avoids exposing the servers (I agree that this may not matter) and
it puts less in DNS, with the cost of one new RPC.  I get the impression
a new RPC is no big deal - it's changing the wire protocol to allow
variable-sized addresses that is scary.