I change the strings on my acoustic guitars about once every couple of months, depending on how often I'm playing them. Normally I purchase phosphor bronze strings. I just like the way they sound, and specifically how they interact with my guitars (Gibson J45 and J150). Most often I purchase Martin 80/20, but I've used other strings such as John Pearse. The strings I used for years are no longer made, they were Kaman Adamas strings. I play fairly light gauge (.12-.54) because they are slightly easier to play, and my guitars already have a ton of low end so thicker strings are no benefit to me in that regard.
I picked up an additional acoustic gig this weekend and needed to change my strings right away so instead of ordering them online I went to Guitar Center. They were out of the Martins that I wanted, but had several rows of Elixir strings. I've heard of Elixir for a long time and I know many people who use them, but I have never tried them because of my apprehension about using coated strings and the fact that they cost 2–3 times more than most other brands. Elixir is owned by W. L. Gore and Associates, the company that makes Gore-Tex and other hi technology materials. I decided to give them a shot.
First of all, I don't play a ton of acoustic guitar, I'm mostly playing electric these days. And when I do play acoustic it's usually in the studio in a critical listening environment. I don't do many outside, acoustic gigs or live performances, and these two factors influence the type of strings I buy.
I purchased some light gauge (.12-.53) phosphor bronze Elixir NanoWeb strings and put them on my J45. After tuning up, I immediately noticed that there is a slight absence of high-end with these strings, most likely due to the fact that they are coated. They certainly are not dull in any respect, but there's some sort of sparkle on the top end that is missing to my ears. Also, I just don't personally I like the way coated strings feel, not only to my left hand (fretting), but also to my right whenever I finger pick, as well as how they respond to the pick itself. The texture feels odd to me like there's some sort of barrier between me and the metal that I'm used to. Also, they kinda feel a bit 'slippery' but perhaps this will decrease over time.
On the flip side, one immediate advantage to these strings is that due to the fact that they are not overly bright, I could definitely them put on a guitar and record it immediately. Most often with non-coated strings, I find that initially they are almost too bright and it takes a few days for this to dull just slightly in order to attain the "sweet" spot in terms of tone. I can't really record a guitar with brand-new non-coated strings because it's so obvious that they are brand-new and they just sound really metallic.
Despite this absence of high-end air, the tone of the Elixirs is actually quite good. They're balanced, without any exaggeration of low end or low mid frequencies. Once I got used to some mild slipperiness, they play very well and probably squeak less than non-coated strings. After a few hours I was feeling more comfortable with them, and was pleased with the overall sounds I was getting whether playing chords, arpeggios or lead melodies. I will have to provide an update in a few weeks or even months to comment on whether the Elixirs hold their tone that much longer than other strings, but initial impressions suggest that they do, and this is been confirmed by several other guitarists that I know as well.
I picked up my other guitar, the J150, at this point for comparison. The strings on it were a couple of weeks old: Martin phosphor bronze. They were still in the tonal sweet spot to my ears, and still had plenty of high end; they also just felt and sounded a little bit more "earthy" which is how I like my acoustic guitars to sound. That's one reason why I bought Gibsons and not some other brand. I don't think they are necessarily the best guitars out there in terms of craftsmanship, but they are in fact very high-quality, hand made instruments, and more importantly they complement my approach to playing. I feel like the non-coated Martin strings at some point just "settle in" and sound really nice for a number of weeks before eventually starting to oxidize and lose their high end, as dirt and dead skin cells accumulate. I guess I like the organic nature of strings that don't have any sort of coating on them even if it is very slight, and honestly since I started playing before there really was such a thing as coated strings it's also probably just a subjective preference at this point.
The Elixir strings are fine strings with great tone and I would recommend them for the following applications:
If you play a lot of live gigs, in public, where your guitar is amplified through a pick up. The slight loss of high-end is negligible, you're never going to hear it through a PA.
If you gig a lot, and don't want to have to change your strings as often, I am fairly certain that Elixir strings are going to last and retain their tone a lot longer. You will probably get your money back from this alone.
If you like the feel of coated strings.
I will probably stick with my non-coated phosphor bronze strings for these applications:
If you play mostly in critical listening environments (that is truly 'acoustically') and are preoccupied with the difference between coated and non-coated strings in terms of their frequency response, and of course prefer the tone of non-coated phosphor bronze strings.
If you prefer the more organic ('earthy') feel and interaction with your guitar that non-coated strings provide.
If you don't play acoustic guitar quite as often and thus will get more mileage out of your strings.