Having access to both you can't go wrong with either. The OS will allow you panning shots when using as a standard tele, and can help with macro if using a small aperture (otherwise the back and forth shake the OS can't do anything about with a razor thin DOF). But if you already have a stabilized tele you won't find the OS nearly as useful--at least $500 more useful IMO. The already fast 2.8 aperture leaves you enough wiggle room, and stabilization usually only works to 1/250 or so.
So for straight macro use, non-OS is adequate and smaller; but for dual purpose as a macro and 150mm tele (or 210 with 1.4 TC), the OS version will do better. Sharpness wise will be sample dependent; both of mine are on par and the size is the biggest difference.