I tried to switch to Colemak once, but it was too big of a change. I did, however, successfully switch to an alternative of the Carpalx QWKRFY layout: http://mkweb.bcgsc.ca/carpalx/?partial_optimization

Instead of 5 swaps, I only do the first three (K/E, J/O, F/T). According to their scoring function, it gets you most of the way there anyways. (Whatever that's worth).

Their rankings of popular layouts might also be of interest: http://mkweb.bcgsc.ca/carpalx/?popular_alternatives