Perhaps the alternate solution when one wants just one lens as a casual walk-about is to take another less demanding body ... but I still am looking for a one lens solution with a zoom that isn't as compromising as Nikon's current offerings.
I think this is largely an advantage/disadvantage myth promoted by determining overall file quality and detail by review at 100% on the screen rather than either a print of a given size or the final screen-presentation. When have you ever presented an image (in final use) as a 100% on screen image?
If you shoot handheld at borderline shutter speeds with a D800 and a D3 and review them at 100% then the D800 is likely to show more camera shake and other "imperfections" (soft corners of mediocre zoom lenses etc). But if you down rez the D800 to the size of the D3 and print them both the same size you'll notice the same or better detail in the D800.
Don't let slightly soft results at 100% at 36mp scare you away! This has been a lesson we have been teaching people in medium format for a long time. When you have, for instance, an 80mp digital back and the results are just shy of perfect at 100% on screen, the detail held in an actual print will still be absolutely phenomenal.
Lower resolution will never capture MORE detail than a higher resolution capture, but when reviewed at 100% the lower resolution capture will often appear crisper.
So taking a "less demanding" camera has some advantages:
- smaller raw file size (am I right that Nikon still
does not have the option for a lower-resolution raw which Canon and Phase One have had for years??)
- easier evaluation of sharpness on the camera LCD
But otherwise I can't think of any advantages. On the images where you have the glass, aperture, and shutter speed to take full advantage of 36mp (i.e. a good prime at f/8 at a fast shutter speed and a steady body) you will have it. On the images where your technique or lens don't allow you to make full use of 36mp you'll still get raw files with as much absolute subject detail as you would with a lesser camera.