I think that this goes some way towards explainng it and is seems more like what works best for the individual rather than any right or wrong
I guess that it doesn't matter so much as you can ony show the same information for each item in the service catalogue anyway as there is only one report template so it's probably best to just keep it simple.
The complexity is introduced when you start wanting to upgrade certain bits of say, a PC e.g. more memory / bigger hard drive etc as you would need a different CI for each configuration possibilty
I'm going to try a Requestable Product object and see how that works out
Still wouldn't mind your thuoghts though guys and gals