PV-GS250 and the PV-GS400
As you said, both are 3CCDs. This is a good start. The 250 is a 3.1 megapixel camera, while the 400 is a 4 megapixel. Not sure if you're after stills, but if you are, there's something to consider. The 400 in my experience produces very good color in nearly all light, while the 250 performs well in all but low light.
It's too bad that the 250 still has low light problems, as it's an improvement over the 200, with new CCDs etc. Speaking of which, we can get a feel for the cameras by comparing their CCDs.
250: 1/6 inch
400: 1/4.7 inch
the 250 has 640/800 pixels video-effective, while the 400 has 700/1000 or...1070 maybe?
All in all, the 250 is better than a number of Panasonics, but it still needs some work, while the 400 performs well above the other PV models and plays level with both sony and canon cameras.
The 400 is not a bad choice at all.