I mounted mega-serious extra lamps on my daily driver a couple of years ago, for sure a big step in visibility. Especially here up north with eternal darkness half of the year and hords of stampeeing mooses in the woods. They are very useful especially when driving long distances with limited traffic (main beam).
But on my Morgan I think about adding them to my extras mainly for looks. In my opinion I found the looks slightly more balanced if the added extra lights are slightly smaller than the standards (but not smaller than the +4SS, then they become "side lights"...). Going down in size also means loosing some efficiency (not including xenon).
As Max5 wrote the one used on the +4SS looks great and the price is OK for lamps and brackets. Assembly should be pretty easy but includes body work drilling
Not sure about the quality...the chrome has a slightly different shade compared to the standard headlight chrome rings.
Here we are allowed to have side lights also in the extra lights (at least i think so...) meaning double bulbs and a nice glow also on dipped beam. And if also wing mounted side lights are mounted...in "side light mode" the car will look like an inverted christmas tree...