I'm not Sprog, but maybe I can answer your question.
The g/f and I laid a 'click lock' floating floor about 5yrs ago throughout our downstairs area over concrete, tiles and old floorboards (the boards were too far gone & i didnt want to rip em all up and relay with new).
On top of all the floors;
- first orange plastic, joins taped and enough left at the wall edges to turn up
- second a foam underlay about 8-10mm thick to provide some sound deadening, to reduce 'jarring' when walking on and to take up any small imperfections.
We have not had any problems with the floor in 5yrs.
We did use commercial grade over domestic, with a thicker veneer that can be sanded & resealed when needed.
The laying of the floor presented no major hassles, just the amount of time to finish off the edges was bit of a chore.
We love the look of the finished job and cleaning it beats vacuuming hands down.
Here's some (not very good) pictures..
The one BIG DOWNSIDE was that the boards being being 2.4 mtrs you need 2 people, one at each end, to 'stamp' them together in unison.
The g/f being smaller and lighter did start to complain about a sore knee but continued on.
BIG mistake she ended up with avascular necrosis, basically killed off the end of the 'shin' bone at the knee joint. Took a few years for her to recover and for the bone to regenerate fortunately if it had not a knee replacement would have been needed.