After the 1.6x crop factor is introduced, how may of the APS-C class lenses are available with the 24-120mm effective focal length with f2.8-4.0 ?
Firstly, the actual R-1 lens spec's are f=14.3-71.5mm, f/2.8-4.8 (not 4.0).
Secondly, converting to "equivalent focal lengths" really only makes sense of you also convert to "equivalent apertures": the aperture ratios that give same light gathering speed (to compensate for the expected difference ISO speed limits of different sensor sizes), and same DOF wide open. The rough rule is simple: multiply f-stops by the same "format factor" as the focal lengths. That is, compare at equal (effective) aperture diameter, or entrance pupil size.
The R1 has a format factor of 5/3 (1.67x), giving
35mm equivalents of 24-120mm, f/4.7-8
DX equivalents of 16-80mm, f/3.1-5.3
Canon EF-S equivalents of 15-75mm, f/2.9-5
FourThirds equivalents of 12-60mm, f/2.4-4
The 5x zoom range is a bit wider than anything in the DSLR mainstream except the Canon 17-85 f/4-5.6 EF-S, with a slight "brightness" (effective aperture) advantage for the R1 lens to be balanced against the Canon's greater telephoto reach and IS (see below for why I consider the Canon lens sightly "brighter".a.k.a. "faster".)
Amongst DSLR lenses with slightly lower 4x zoom range, the tele end of the R1's lens falls just short for brightness compared to the Nikon 18-70 f/3.5-4.5 DX or Olympus 14-54 f/2.8-3.5, at least at the telephoto end where lens brightness is most important.
In fact all four lenses have similar light gathering speed at the telephoto end, judged by effective aperture diameter (focal length divided by aperture ratio), with the R1 lens the "dimmest" by a small margin:
15.6mm Nikon 18-70 f/3.5-4.5
15.4mm Olympus 14-54 f/2.8-3.5
15.2mm Canon 17-85 f/4-5.6
14.9mm Sony/Zeiss 14.3-71.5mm, f/2.8-4.8
The slightly wider coverage than the others appeals to me a lot, and the 5x zoom range is a nice little edge. Then again, both of these are far more important on a camera like this that does not allow one to swap to a wider or longer telephoto lens.
Going from the prices of those other three lenses, I can accept that this lens alone might be worth around $500, so you effectively get the body for an impressively low $500. If the lens's optical qualities like low distortion are as good as I have read in some places, maybe it is worth more than that.