Invoking Occam's Razor is tricky business, if you ask me, since it is usually misinterpreted. The ever-vigilant Wikipedia informs us that, strictly speaking, it is a "principle that suggests we should tend towards simpler theories until we can trade some simplicity for increased explanatory power. Contrary to the popular summary, the simplest available theory is sometimes a less accurate explanation."
As FET currently stands, I do not see much evidence of "increased explanatory power" over RET. This in itself proves nothing, except that invoking it lightly seems arbitrary.