[glend (Glen)]

Allan I have a SQM-L and wrestled with that question when I considered my purchase. I resolved it in favour of the SQM-L because my observing site at home on Lake Mac has stray light sources, like a pesky street light on a hill , that I can shield the scope from but would potentially influence an SQM wide field reading even if only through humidity scatter. My reasoning is that a lot of my observation is quadrant related and the L allows discrimination as to where the best viewing is, for example is Orion better tonight than last night. I can always do a few other readings, which literally only take a few seconds, if I want a wide reading - and this allows you to examine the sky in 20 degree cones to potentially identify the effects of your local light pollution sources. This ability to discriminate, or map your local sky in cones is a big advantage when your deciding where to point the scope. If I take the SQM-L away to somewhere like Bretti then functionally there would be little difference with the standard SQM as the whole sky is dark. When I spoke to the Unihedron guy, via email, he recommened the L for suburban users. Hope that helps. Btw my best readings here have been above 21 at zenith, which is considered dark.

Glen