I am a long time Elixir customer (thanks to Thomann) for a good set of reasons.
I only play at home, so I am not able to judge these strings under daily-gigging regime, although I feel they would do that just fine.
1. Why do I stick to Elixir strings?
Thanks to their coating the strings will stay cleaner, there won't be any oxidation unless you have brought them to the point of nearly falling apart.
The coating retains a slick feel to the touch (like when you put FastFret on strings), which is something I really love, makes sliding and moving around the fretboard so much easier.
In 20 years of playing, with any other brand, it start feeling like I am grabbing on rusted iron as soon as my hands start sweating.
The durability is great as far as I am concerned. I play nearly every day, 2 to 3 hours each time, and I have gone as far as 6 months with a set or single string without having to replace them. I know this may sound crazy, but I am also the type of person who cleans the strings one by one after being done playing, so there is an element of care right there that possibly allows me to stretch out the durability. However even without care, they will last 3 to 4 times as long as standard strings. I use to change strings every 4 to 5 weeks.
Sound-wise they mostly feel really bright when just installed, like all strings do. Once settled they loose a bit of that brightness and they kinda set into place, balancing out the frequencies. This stage will last pretty much until the strings start deteriorating and giving up, which in my case means months.
All in all I can never say how much I love this brand, it's just so good to my opinion, and if you like what you have read above, you should definitely give them a try.
