I also think that the Swarm Host just needs a few tweaks, and it will be perfect.
I would personally like a little more health, a little less DPS, and a slightly faster spawn rate, I think this would enable it to reward micro more (as in unburrowing and reburrowing faster, since the locusts come out quicker).
This game played by Reketan makes Swarm Hosts look awesome, truly able to contain and punish a turtling Protoss player, do you know how long I have waited to be able to actually punish a Protoss player that wants to turtle to a deathball?
Look at that beauty, not only does it require high apm to use effectively, it is pulling the Protoss ball in every which direction, and taking losses everytime, small losses, but losses.
I for one cannot wait to be able to actually dictate the pace offensively in a ZvP, so no, I would rather NOT have Lurkers.
Although I like his trick of keeping Overlords on follow and 'Poop Creep', that game is quite a far cry from a typical ZvP, and the Protoss wasn't quite following a, shall we say, 'strong' game plan. The Protoss wasn't upgrading early, went for a 6-Gate other than either Stargate or Robo after FE, and still attempted aggression upon scouting a lack of a third. Rek also mentions that the guy always does the same build on that map.
I'm 68% ZvP right now at high master/GM MMR, and I make swarm host probably 95% of my ZVP. I'll keep casting more till people quit calling them bad! :D