"i overpowered mine by 300 true watts for 16 months n never had a problem best subs ive ever owned"
And if the power ratings on any speaker really meant anything this would matter.
"he design in the middle is funtional so little distortion"
The dust cap!? Or did you mean the voice coil and magnet, most of those are functional

As far as the dustcap yea, its functional it keeps dust out.
"they have rubber surround not foam"
I have woofers going as far back as the 60s with butyl rubber surrounds, not a big deal. And as far as stiched and not glued. I've glued on many a surround that I dare you to try and pull off the cone. you wont be able too.
A friend of mine has a pair of alpine subs, the surrounds came off one day when it was really cold out, So i reglued them. Its been 8 years and their still on there
If cheap companies used real glue they wouldn't be having problems and having to come up with gimmicks IMO.