Forgive long post in advance....
pageone - Thanks. You make me blush. ;) The respect is mutual. First, my understanding of servers and server protocols is minimal at best, and if I've come to know anything in the area, it has been by relentlessly asking stupid questions until the answers all added up for me. You're a good person to ask.
I wasn't doubting your cautions about the 200 protocol. I simply didn't know what the 200 did besides returning "OK," and that's what I was asking. Now that I know a 200 returns a mirror domain, which as I'd mention is to be avoided, I'm in complete accord that it should not be used.
To clarify for beginners reading this thread, you don't want the same site displayed under two different domains. If you point or forward domains to a site, they all need resolve to the main domain of the site. If they don't... if you have the same site displayed under different domains... you're asking for trouble. The multiple sites are called mirror sites... are treated as duplicate content... and there will inevitably be linking issues. On Google, the site with the highest PageRank will survive.
Also, to clarify for beginners, any domain redirecting needs to be done on the server, not via meta refresh or other browser side redirects.
Now, the 301/302 issue for parked domains is a little cloudier, at least for me, and eventually I'm going to cite some posts in one of my learning threads from two and a half years ago.
The gist of what everybody who's discussing 301s vrs 302s here is saying is that 301s pass PageRank and link relevancy, and that 302s do not. Agreed. If I have a client who's built several mirrors or superfluous sites on tld variants or whatever, and there are some existing inbounds to them... yes, by all means I redirect them with 301s and preserve all the link benefits we have.
However, if you have a bunch of parked domains... never been up on the web... or domains that have no inbounds... well, there should be no existing link benefits, so you're not preserving anything with the 301s. There may, however, be a problem with Google when you point too many additional domains at a site. I take WebGuerrilla's msg #17 in the thread below at face value....
Pointing multiple domain names to main site without mirrors
How to do this without hosting them separately and using 301s?
In the same thread, andreasfriedrich goes into how to deliver the alternate robots.txt and then goes on to posit that 303s might in fact be the best redirect to use if you're pointing a great many domains. I've cited this before on the forums, and it's not aroused much interest, as no one's apparently had trouble with 301s.
To bring this all back to the original question:
Since we're talking about new parked domains, what is wrong with the 302s the registrars generally provide? It seems to me they would be avoiding the problem of passing PageRank, which Google doesn't like in this kind of setup. In some hosting situations, enabling the domain forwarding (302s) is a lot less fuss than setting up the Rewrites.
As you can see from the above, transferring that credit is in fact my concern, though probably not an issue with 3 or 10 or 20 domains. Maybe more so if competitors link to them. What's the possible issue with linking to the 302s? It wouldn't pass on anything except for traffic.