Well, it might not be horrible but it definitely won't be the best of both worlds. The collective bass will be soggy and indiscriminate at best, although you will certainly increase output.
A sealed woofer and bass-reflex woofer have different phase responses. A woofer and a port output in the same enclosure have different phase responses, although each emphasizes a little bit different range (the woofer has decidedly less excursion and less output through the port's resonance range). A direct radiating sub under the driver's dash has a different phase response than a sub concealed within an expansive port locker and vented via some form of grill. So the result will be phase soup, just as if each and every entity is a different distance away from each and every listener.
Good SQ bass requires good tonal construction which is very much dependent on the coaxials for the midbass contribution. It's a lot easier to manage a smooth transition through tuning with a single woofer location and single phase rotation. With multiple woofer loading types, orientations, boundaries, and locations, its impossible. Also, SQ is dependent on balance so when the subwoofers over-drive the coaxials' midbass contribution, you can kiss SQ goodbye.
Who knows what your definition of bass SQ is and what type of music you listen to. If it's a steady diet of Rap, Hip Hop and Electronic Techno, then SQ is less critical. If it's real string bass instruments played by real artists then it will be extremely disappointing.