Ree et al. 2005/Ree and Smith 2008 rate matrices

I was wondering what information would be possible to incorporate in the transition matrix of Ree et al. 2005 constructed by simulation that would not be possible to incorporate in the rate matrix of Ree and Smith 2008. For example, in that paper the absence of a dispersal route between areas at certain times was apparently successfully modelled in the Hawaii example (by setting certain rates equal to 0?). I would think that if you had prior information about the relative probability of dispersal in different directions you could take that into account, for example either by constraining E->W dispersal to be a certain fraction of W <- E or estimating the two rates separately. What kinds of information would require a simulation approach to incorporate?