An AMD 7950 or the Nvidia GTX670 would work well for you, the issue with displayport adaptors seems to be improving over the last year, although we do still hear of some tales it is nowhere near as bad as they once where.
You can check out our reviews of the
7950 and
gtx670 for some comparisons on performance and thoughts about each card.
However Nvidia will only allow a 3x1L setup, no protrait support yet.
Personally I prefer 3x1L over 3x1P, however 5x1P does look impressive.
Eyefinity will support both 1920x1080 or 1920x1200 in both orientations
Once you have decided which card you would like to use and the configuration of monitors, we can certainly help you further with the cables you may require to make it work including any displayport adaptors that are known to work well.
As for displayport adaptor reliability, I have only needed to replace a single VGA adaptor out of my collection of 2x vga, 4x dvi adaptors since I got them back in early 2010.