jackson just came out with a really sweet seven string soloist that might be worth checking out if you like a really thin neck, and can afford to buy it. Check there website and look for it under the soloist models and you will find it.
I agree I have had several guitars and always question selling them but you can always find something you like to play better, my friend got a 200 dollar Epiphone SG and he loved it. I would recommend looking around to find a guitar you really want and then see if you want to sell your jackson. My biggest advice is to keep it till you find something better and then sell it.