All of Duke's TC cabs sound:...are the sonic benefits really that great, above a high- quality 4x10??
I've got a Golight 4x10 that sounds very, very good, and it weighs 54 lbs.
Yes it's bulky, the midrange dispersion isn't the best, but it does really sound very good, and is very loud.
- more open, less "congested"
- richer in the range from the open E down to the low B
- more dynamic, and less compressed on big hits
- more even from note to note
- more articulate
- more consistent (less affected by difficult venues)
Individually, the differences are pretty subtle, but collectively they add up. Plus, as you point out, these cabs aren't bulky like your 410, and they have better midrange dispersion. So on a technical level, yes, Duke's cabs really are better.
But we're talking about tone, so it's as much art as science. Your Golight has a fair amount of cone distortion at high volume, so it's going to add some "growl" of its own, that a Thunderchild doesn't provide. The low B isn't as impressive. It also compresses more at high volume. But depending on what you're after, these characteristics might be better, worse, or simply irrelevant.
In the end it all comes down to what you want. Do you have roadies? Do you have a B string to worry about? Does your favourite bass already give you all the growl you need? Do you think you'd like to hear the sound of your bass with a little more clarity? Would your drummer and the rest of your band like to hear you a little bit better?
Perhaps most importantly, does the idea of putting your current tone and technique under a magnifying glass sound inviting or intimidating?