Hi Bob, I have a Sekonic L358 and the 1 spot finder and I find the attachment to be a very useful additional although expensive addition to the meters capability especially outdoors although I'm not a good or dedicated landscape photographer I find it excellent for assessing the contrast range of the subject by spot metering the highlights and shadows, also metering specific areas of my sitters faces when shooting outdoor portrait especially in back lighting I can meter the subjects face and the background from a distance without shoving the meter in their face.
I.M.O. spot meters are very useful tools in the hands of someone who has an understanding of the basic principals of exposure and sensitometry and that meters only read 18% grey, but in the hands of an absolute beginner can be dangerous, and that photographers were still shooting good outdoor pictures before they were invented, I managed for about forty years before I owned one.