Awhile back I read an Iams article about cats and vomiting and it suggested putting an object in their bowl to slow them down, and also elevating their dishes. Sometimes Symon gobbles his food down and immediately throws it up. We tried putting a giant 20-sided die in his dry food, but aren't sure it worked. We also put a coaster under his food dishes, but that wasn't elevated enough.
Finally it occurred to Steve to try my small exercise step. This appears to have been the right thing. It's been a few weeks and he hasn't thrown up yet. We'll see if this works long-term.
Here is the step:
We put a towel on it to keep it clean:
Symon was skeptical at first, but he got used to it:
*Crunch* *Crunch* *Crunch*
November 2013 Update: Symon still gobbles his food and throws it up immediately very occasionally. Maybe once every couple of weeks. We think he's stressed when he does this (due to rain, wind, etc.). So I would say the elevated food dish is worth a try. Not perfect, but it helps.