I think, that Sony HBI-900 is a very nice device. It has very high quality analog picture, but MSX2 video chip limits the colors to 256. It can take up to 2 video signals in and do not have problem digitizing PAL pictures.
Actually I think, that if you trick a bit, you can even digitize interlaced pictures in overscan mode, but I've not really tested this. (You can find example of overscan code from:
users.skynet.be/bk263586/Demos.htm)
HBI-V1 is very nice device to use software vice, but it does not have any reasonable picture adjustments, PAL signal is problematic and it is much too easy to break. (Killed the video hardware already twice)
I have not very much Phillips 8280 usage experience... There are basic video adjustments that are typically enough. Anyway the really nice thing is, that you can use Phillips videographics for digitizing. I like that software very much!