On horns that I already like, the tone halo doesn't seem to add a lot other than weight. I can feel the sound resonate off the sides of the bell less and that's about all. It's like adding a counterweight tk a horn that doesn't need it- things change but not in a necessarily positive way.
On horns that need some help (like this 830 and a friend's 448G), everything is improved. The bell doesn't waste energy vibrating on problem notes, the sound has more density, and on the 830 especially response is improved all over the instrument. I have been using it all the time at work; yesterday i let another band member use it for a set and the difference was dramatic on my end. The horn was markedly worse.
On the 448G, the sound difference was immediate; my friend reported feeling different feedback of course, but we heard a much more centered, less diffuse sound on the other side.
The weight balance change is not great. After all, it's like adding a screw ring to a bell. It's going to add weight way out in front and to the left.
Here's a super duper high equality photo of it on the work 830:
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