I like the ES a lot. That said, there are too many other pickup options out there to ignore. And for just the occasional plug-n-play, the expense of
adding the ES to a guitar that does
not already have it is difficult to justify, IMHO.
As Michael said, the LR Baggs Anthem gets lots of love, but frankly I personally like all the Baggs stuff that has come out over the decades: great company that offers good quality/good sounding products in my experience.
I am in a somewhat similar circumstance as you with my RTaylor that I'd like to amplify, but simply is not my primary play-out acoustic (not to mention I'm tapped out after said purchase and just need something inexpensive

).
Lots of folks love the K&K Pure Western Mini. But check this out: someone on the AGF recommended buying the transducers from these folks:
http://www.jjb-electronics.com/prestige.htmlThese are said to be the same units, but at half the cost! The way I see it, at $50 smackers for an unobtrusive system on a guitar that I will plug in only seldom, I can't miss. FWIW, that poster recommended the the smaller 15mm transducer (instead of the 20mm) if you want less bass or your guitar has lots of bottom end. I'm going this route soon, FWIW. Hope that helps you a bit.
Edward