Wait a minute, that's my job.
I had a thread where I was hacking games to double experience and gold:http://www.romhacking.net/forum/index.php?topic=25345.0
I didn't post about Phantasy Star 3 but I actually have working patches for Phantasy Star 2, 3 and 4 which I've not posted about. Now that you've mentioned it, I guess I should start releasing them.
I just didn't want to release them without proper testing. Maybe later I'll upload it so that you can test it and tell me if it's working properly? I never played the game, you see, just hacked it.
Incidentally, I don't know what that editor you mentioned actually does, but my patches change the assembly instructions to double the amounts as they're loaded into memory, rather than painstakingly modifying every amount for every enemy. As for why nothing happens for you, I've no idea.
Give me a few hours and I'll upload my patch for you to have a look at.
EDIT: here you are! Patches for Phantasy Star 2, 3 and 4. I've only played PS2 at length in the past, so if you know if there's anything else in the other two games that I should know about, please let me know. s346165667.websitehome.co.uk/psyktrans/phantasystar234.zip
I understand that my answer to this topic doesn't really answer your question...
But given that you wanted to double experience and gold, I figured I'd let you know that I've already done it. If you want to know anything else, maybe I can help.