You ask about the reliability of the IGI as compared to the microfilms of
the original records.
The IGI is only a directional guide and you should not rely on that to
provide ultimate information, only as a guide to where you might find
The microfilms / fisches of original Scottish records made by the Mormons
(although not always readable) are far more reliable.
Duncan Beaton, the Scottish contributing editor of the Clan Campbell Society
(North America) quarterly magazine recently wrote an article (which I
published) on the subject for that magazine of which I am editor. He wrote
the article due to his concern over the 'corruption' of the IGI files since
people could add to them without giving their original sources. He found
instances where people - keen to make a 'Scottish' connection - had
basically taken a leap in faith with their genealogy and inserted
information to link to a known character whom he had in some cases already
proven had no such children.
That is a concern with the Campbell marriage data base - that there is no
control over the quality of information provided unless everyone gives the
source for their information. If the sources are given they can be checked
in the original or in a microfilm or transcript of the original.
So the IGI continues to be a most valuable guide to what information may be
available, but once you find some information there it is essential to check
it in the orignal sources - and then of course quote those sources in your
family history, or it might all be fiction to future generations - or at
best be a guide (like the IGI) for them to use to find the original sources
themselves (if they survived).
I hope this is some help.
All best, Diarmid