I haven't seen the Meridian slit scanner, but we did get the Bio-Rad slit
scanner in for an afternoon last winter.  It was a very impressive
instrument. You should check it out.  We put a 400 micron slice of diI
injected brain, in buffer - not cleared in any way- on a slide and were
able to focus most of the way through it.  Resolution was sufficient to
observe dendritic spines on Purkinje cells.  And all this in real-time!
        We put the same slice under a conventional fluorescent microscope
and the effect was like seeing a flashlight held up against a sheet.  Only
the surface neurons were visible, and they were poorly resolved glowing
circles.