No brainer, get the 530. The x20 series had some issues with a blotchiness on the s-video inputs which was corrected at some point, but you'll take a chance because there is no way to tell which have the problem. I have a 530 and I see no softness on it. Any supposed softness is possibly due to the fact that the factory default settings in the service menu are very different between the 20 and 30 series Elites. Below are some of the advantages the new elites have over the old.
1. 2 DVI inputs 2. Accepts 720p signal, upconverts to 1080i. 520 will not accept a 720p signal. 3. New Pioneer Pure Cinema III line doubler. Allows the user to select to view sources in either 480p or 1080i. I personally can't tell much of a difference between these two. 4. Redesigned User menu that is extremely easy to navigate. 5. Redesigned service menu that is more flexible. 6. Has a "Pro" mode which allows user to more fine tune settings. I don't see this as a big deal. 7. Anti-reflective protective screen. 8. Improved Blue gun. 9. No red push according to Dave Levy, a calibrator on the Home theater spot who has already ISF'd several 30 series Elites. I believe the 20 series had some slight red push that is not correctable with calibration.
I love my Elite. The only thing that I really don't like about it is that the speakers on it are pretty crummy. They aren't good for much. If I were you, I would definitly go with the 530.
The 30 series actually have the same lenses, except for the Blue lense, which is quite a bit more of an extravagant USPL lens than the other two.
There is a hint of Green push on the 30's, but it isn't offensive. There is not much to calibrate on the DVI input, compared to the 33K and 45K inputs in Service mode, but that is minor. The reason I mention this, is there will no doubt be a plethora of DVI output products appearing on the market shortly, and if it parallels that of the HD set top boxes and D-VHS recorders, it is likely that the settings for the output stages are going to be all over the board as we have discovered through Joe Kane Productions (David Abrams is welcome to chime in on this )