I don't think that porcelain grates are as good as plain cast iron because
well seasoned cast iron is practically nonstick. But cast iron rusts easily
even if seasoned if it gets wet and is not dried off. I've got cast iron
pans that have been well seasoned longer than I've been around and if you
clean them and don't dry them off then they will develop a small 'dusting'
of rust (only the machined inside). The way most people (not just grilling
amateurs) care for their grilling stuff, cast iron could be a maintenance
nightmare to most. Of the 3 reasons listed in the post above as to why they
exist, rust is the only issue that PCI actually addresses. It doesn't have
anything to do with the food sticking or not sticking. It doesn't affect
cleanup that much except for not having to give your grates a light coat of
oil after you brush them off.
Using PCI grates gets you the heat retaining benefits of raw cast iron
without the maintenance hassle. Porcelain is not going to just wear off in
general day to day use of the grill. Most people would have to really abuse
their grates to see any degradation in the porcelain surface. If you treat
PCI grates the way madmakr says you should treat CI grates you should never
have a problem. If you buy quality porcelain grates, they will last longer
than you will.
As to never seeing pros use porcelain, it depends on what type of pro you
are talking about. Pro grillers? Maybe, maybe not. Pro chefs, yes. And
they use all types of utensils in them without damage. Le Creuset built an
industry on it. Lodge and many others offer it. The main reason more
companies don't offer it is cost. Porcelain coating isn't an inexpensive
proposition. Manufacturing cost vs profit is probably the real reason BBQ
Galore is phasing them out. They never have shied away from making as much
money as they can.
What would I buy if given the choice of the two, probably the raw cast iron
but certainly not because I think PCI is garbage. I might not buy CI though
because most aftermarket (and many OE) CI grates out there are poorly made
with excessively large 'pores' in the metal.
All that said, I do love my CI skillets and wouldn't be without them. As
madmakr said, very easy to clean.
He also mentioned a CI wok. If you truly want to wok cook, don't buy a cast
iron wok. Don't buy an aluminum, or a copper, or any of the brands of
'clad' woks that are out there. Buy a plain steel wok like you find at the
Asian markets. The whole point of a wok is to have a very hot spot in the
bottom and continuely cooler sides as you move away from the bottom. CI and
the others list just distribute the heat too evenly. This is the one pan
that you do not want even heat distribution.
"Of all the imaginary friends I've had, I don't think there was one that I didn't end up having to kill."
in seach of Umami