I've dwindled my options down to the SSA GCON 15 and the FI SSD 15 (based on price and the power I plan to use.) So i'm going with 2.5cu sealed for either sub on 500-750watts. I'm just need some options on which would be the better overall sub for my application. Or if the difference won't be that noticeable.

Well what is your application? Are you looking to squeeze out every bass you can, or are you looking for a flat respone and a good overall sound? Either way, there really isn't much of an difference. If your looking for which setup woud be louder, there really won't be an difference if this is just an average install. If you have the room, I would suggest ported. But then again, I just don't know your style.

This is going in my car. Im a sound quality person. I like a good ported setup but Im not into numbers. Im looking for the one that will sound the best. Although I know probably no one on this forum has heard them both under the exact same conditions.

Yeah, I doubt you will be able to get an opinion, based on those two drivers. Even if so, they will sound different in your application. I know the Icon sounded crispy clear. I suppose just do some research on the ssd, and go from there. I know a select few have already gotten their hands on the gcon, and love them. Both drivers listed above will sound great. So it may just come down to cost, like shipping and all, or just which brand you think would look cooler maybe? haha. But in all serious, you can't make a wrong decision here.

Either way, there really isn't much of an difference.

At 2.5cuft net, the difference is in the low frequency roll off. The SSD will be down 3dB at around 60Hz and the Gcon 3dB at 45Hz. For the application at hand the Gcon wins for sure IMO.