The best scaling for three 1920x1200 monitors would be to run them at 3840x768, which is triple 1280x768. 1280x768 is 16.67:10 instead of the native 16:10, but it's close. If Matrox offered a triple widescreen resolution of 3840x800 it would be perfect.
If you want to see real screenshots and images of the TripleHead
2Gi in action, check out
Paddy's Review here and
my review at SimHQ.
IF you get the 2407 you will have a monster monitor that is great for watching movies, but you'll only have one of them; you'll miss out on all the thing you can do in 2D on multiple monitors, plus your gaming won't extend into your peripheral vision like it does in triplehead.