I've seriously thought about "getting gelled" and may still do so. It's just I heard a definite improvement in the sound with the alternate tuning even with the un-gelled drivers. I'm a little afraid of screwing up the sound with a mod that is not reversible, that is without getting a new pair of drivers which is not cheap. On the other hand I'm VERY curious how they sound given Steve says they sound better.
Here's one quick tweak you can easily try if you have the alternate tuning in place and want to see at least what the added driver mass makes to the sound. Stick 2" strips of electrical tape onto the driver in four places - at 12, 3, 6, and 9 O'clock. Don't worry, the electrical tape comes off without messing up the driver cone. The tape strips should go out radially from the cone center to the outer edge like the hands of a clock. I don't know how much mass the gel wax adds, but it's probably more than 4 strips of tape - so you can add more mass by making the four strips 3 or 4 layers of tape each before applying them to the cone.
Now, I'm sure this will not sound exactly like the gel-wax, especially since it probably won't effect the midrange much. But it may change the bass sound, and might mellow out the high end a bit. I'm not sure, as I haven't had the time yet to play with this.
By the way, regarding the Deflex material...
partsconnexion has many more shapes, sizes, and prices on it than does Madisound.