Recent work by Finnoff, Strong and Tschirhart (2008) tackles the problem of how to incorporate a dynamic optimizer into the General Equilibrium Ecosystem Model (GEEM). In all of the previous work that uses GEEM, all individuals within the ecosystem are net fitness maximizers. Much of the other literature that models rangeland, in particular Boyd (1991) and Huffaker and Cooper (1995), assumes that cattle follow the Michaelis-Menten satiation grazing equations. Unlike GEEM, the Michaelis-Menten satiation equations are akin to cattle having lexicographic preferences. This simple change in the assumptions of cattle behavior do not allow us to directly compare the work of Finnoff, Strong and Tschirhart with that of papers such as Boyd (1991) and more importantly Huffaker and Cooper (1995). This paper closes that gap between these two strains of a similar literature as well as considers an alternate grazing decision based on proportional grazing. Since the species composition will vary depending on fitness net energy maximization and lexicographic preference maximization, we may obtain different steady states or transition paths. This work identifies the key potential drivers that have been consider for invasion but also identifies an alternative path way that previous literature has failed to recognize. Finally, we consider a simple experiment using remote sensing data from Boulder County, Colorado to potentially eliminate some of the reasons for invasion.