The dialog maker does work with ArmA and I have used it extensively to make ArmA dialogs but I have to do some tweaking after to get them to run error free (not too too much though). If I remember correctly that error message is probably related to one or more buttons in your dialog (it is one I ran into too!). ColorDisabled is required by ArmA but I don't think was there in OFP (or at least not the dialog maker).
As far as what works and what won't it'll have to be trial and error. The
Dialog Control page on the Biki will probably help you diagnose easier. One think to be sure to remember is to add ; after all the dialog controls properties, the dialog maker does not do this for all of them.
What I find most useful with the dialog maker is being able to place the controls with the mouth and have them snap to the grid as opposed to messing with x,y values (although a little of that is necessary) so it is still very worthwhile.