Should I get an Apple 20" display?

I think the general consensus on display rumors is that new displays will come out when new Power Macs come out, probably within the next 2 or months at most I think.

As for the display being comparable to your current CRT, well, I've never used that CRT, but the 20 in cinema is a very nice display. If your current CRT is dying and you need a new display, maybe you should go ahead and and get a 20 in. Even if it's out of date soon, it will stand up as a very quality display for quite a while I'm sure.

However if you're not feeling too hard-pressed, I'd wait until at least after WWDC.

 

20" Sony Trinatron vs. 17" Apple FPD

I have both, and I would say the 17" flatpanel is equally as sharp as the 20" sony, especially married to the digital display card in my G4. However, on the downside for the apple display, the blacks are not nearly as black. You can really see the difference when watching a movie in a darkened office. Also, the blues are off hue. I don't notice it normally, but put the two beside each other, and you can tell. Also, when I print photos, the 20" sony does a better job at matching the colors (expecially the blues) to the printed output. I'd say unless you are doing commerical color work, the apple monitor is quite nice, much lighter and smaller and it is better ecologically both now and when it dies. If you are doing commercial color work, you'll be happier with a CRT and a color calibrator tuned to your chosen output device.