Hello Ro Ro, Just a little thought here.. you can create a whole range of storage that doesn't involve having something under the sink! Or you could have a back to wall floating unit.. Small and rectangular.. It does not have to look like they do now.. Also with certain taps you do need to look at the water pressure, if you want aerated taps etc.. If your taps have a good flow I am sure you won't have a problem.. :))

All would go fine with your combination. I'd advise caution with the darker finishes if you are in a hard water area.

Are you removing the current basin? You have spent all the money on a bottle trap to be exposed and if it was going in a vanity you could have just had standard white pvc fittings.

Obviously a wall hung unit would show more of the floor so would give the illusion of more space but a floor standing unit would conceal the boxed in pipes, the sink pipes and would give you more storage. A bathroom fitter would be able to fit the unit neatly up against the box. But you would need to choose a unit that can be modified easily.