These subs are still going strong. I tend to use them in a mono arch configuration down stage and have found that it is helpful to strap them all together as one big unit because they tend to want to walk around when you are whooping on them. before the strap thery would move as much as 8 inches to a foot out of line with each other over the course of a show.
Other than that my only regrets (rather small) is how well i attached the interior casing around the handles, so far i have had to re attach 3 of them... All in all not terrible but in hind sight i would have been more thorough attaching them.
We have done several radio festivals here in philly with all 12 of them outside accompanying My D&b Q series rig (11 boxes a side) for crowds of 5000ish and most guest engineers have been satisfied. many assume that I have B2 subs (with the knowledge that they are using a d&b rig) and I usually just let them go on believing it, though I never out and out lie about it if someone asks.
I have no regrets about building these, they have and will continue to serve me well.