orange-1200,
Just because it's in wiki doesn't make it a good idea or offer improvements to handling.
My car, before I bought it, was originally setup with 120y leafs (one leaf per pack - rear spring hangers moved further back to fit) and coil overs on the rear and, this was done with the intent to use for circuit racing, they removed it because it had an adverse effect on the handling quality. I was left with cleaning up this mess when I bought it and have gone back to standard and it handles much better now.

There are some good books out there that would help with understanding of the inherent limitations with leaf spring setups and how to tune them to make it work. Milliken and Milliken "Race car vehicle dynamics" springs to mind (This is my reference book when I get stuck).

I'm not saying you can't make it work, but it would be difficult and iterative (changing spring rates on both leaf and coil and also shock valving, Which means expensive). In my view it would provide one, maybe two, foreseeable benefit over standard leaf spring. That being the ability to adjust the ride height up only (really once set you never change anyway - I never have for street on my coilover fronts). May provide benefit to reduce axle tramp?

The negatives would be: difficult to match leaf spring to coil spring rates to get a balance (two springs in parallel changes the oscillation frequency compared to one, therefore you would need to re-valve the shocks to suit), would require very soft coil springs and therefore actual upward adjustment would be limited, extra stress on shock mount points (Now carrying load - as indicated earlier). softer leaf spring reduces leaf resistance in roll, may need to then add ARB.

Does not address inherent deficiencies with leaf spring being Ride and roll are still coupled, Roll steer still present, Potential roll centre height issues still present.
Therefore you get to change rear ride height, added weight, made the rear more complex and done nothing to address the leaf spring geometry issues.
This is my reason for not seeing the few pro's outweigh the cons.