no? If I wanted a sub to use in a sealed enclosure that would be my first and almost only choice. XBL^2 motor topology, faraday rings, alot of xmax and they will work fine in 3 cubes... Basically a xcon for half the price minus a little bit of power handing and xmax, but if you going sealed then massive power handling isnt' all it's cracked up to be. Plus I have a bit more faith in Kevins ability to engineer a driver than I do most subwoofer companies, especially most car audio oriented ones. The xcon uses faraday rings but then doesnt' even list a Le value, that' s a red flag in my mind....
The GTI is a nice driver, but fairly expensive and at least according to the klippel measurements isn't a match for Tempest X, again outside of powerhandling, the dual drive system seems to help alot in that regard. That being said they are both nice drivers, I just feel the Tempest X is a better driver and cheaper, hence much better buy.
DC LVL 3 and the Fi Q are basically generic drivers. No BL or Le optimization that I'm aware of. For a sealed application for keeping SQ at high volumes and high excursion levels they probably woudlnt' be my first choice. Again, the FI Q in particular is a very nice driver, just nothing remarkable about it and when you can get a Tempest X for 250 why not?