Forfarian,
I have read your article regarding SP and other sites and totally agree. However, a bit expensive and the different spelling of names does not help.
It's a lot cheaper than the corresponding services in England/Wales, Australia, New Zealand etc. And there are great swathes of the world where there aren't even indexes. Let alone free-to-use ones.
And you can search with wildcards - for example b*c*n*n should pick up all variants of Buchanan. You can't do this on all of the corresponding web sites, so you have to search every conceivable variant of a surname. And in some commercial sites it can be difficult to narrow down the search to what you actually want.
If it's not on Scotland's People it's unlikely to be on any other site, because (as far as Scotland in concerned) almost all of what is on the commercial sites is indexes or transcriptions of originals that are on Scotland's People, so any record that has not survived to be made available on SP is not going to be available on any of the commercial web sites either.