Hi Mantal-
It depends on what you are expecting. It will likely sound different from any wood guitars you have. Some people think that's a negative. I find it to be a positive.
I also have a CF Journey OF660, which sounds completely different from my Emerald. Just as in the wood world, CF guitars from different manufacturers will sound different, and it comes down to personal preference.
I have an X-20. The first thing I notice when I pick it up is how comfortable it is because of the careful design considerations Emerald makes. The sound is unlike any of my other guitars, which is what I was looking for. The X-20 has a deep rich sound. I'd say not as well articulated as some of my wood guitars, but certainly not muddy. I'm sure others will chime in about the X-7.
And of course there is the advantage of not having to worry about humidity and temperature.
As far as resale goes, I kept track of selling prices (mostly on the AGF) of used Emerald's when I was first looking at them. Like most guitars, the used ones go for around 80%±5% of the new price, though that can be lower or higher depending on if the guitar has options that most people want, or don't. It sounds like you are buying used, so you probably won't take a financial hit on it if you decide it doesn't fit.
Have you looked through this thread to see if there are any X-7s near you that you could check out?
https://www.acousticguitarforum.com/...d.php?t=646425