Although Rawls sometimes seems to see the quest for reflective equilibrium as basically a cognitive process involving the weighing of pre-philosophical beliefs against philosophical theories, the sentimentalist conception of reflection involves a holistic attempt to reach an equilibrium on which the faculties of reason, feeling and imagination can all settle in harmony.
This may reinforce the thought that there's something fundamentally flawed about a conception of rational warrant that we wouldn't want to live by (because it contradicts preferences that stem from love, for example).
To relate this to the vexing problem of 'Moral Roots and Alienating Aspirations', I guess the sentimentalist will be more rooted by the emotions he starts with (though they may be revised to some extent), whereas the rationalist is willing to countenance a far more radical critique of her prior affective responses, in light of what can be justified by universal reason.
How would you assess the two competing views? (There's some sense in which I find the rationalist more admirable -- certainly more noble -- though sentimentalism might be advisable insofar as it's probably a stance that's more conducive to happiness, and perhaps even to 'living a good life' more generally.)