The ES electronics have major reliability problems. I can't even begin to tell you how many of those things we've had to repair, but for the last few years we have had at LEAST two or three in a week. They send us parts by the case load.
On top of that, I think they sound like crap. But of course, that is just my opinion. Make your own judgement on that one. And of course, I am not fond of the Taylor sound in the first place.
It is also worth noting that while the Expression System is highly prone to needing warranty repair, Taylor is exceptionally good at providing those repairs. They have warranty centers all over the place, and they provide those warranty centers with exceptional support. I may not like the sound of their guitars much, but I have nothing but good to say about the COMPANY. Good people all around.
Personally, I think you would probably be much happier getting a Fishman Matrix Natural I installed in whatever you buy. At the very least, I have seen FAR more customers who are happy with Fishman units than with the Taylor ES.
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"Cowards can never be moral."
M.K. Gandhi