Suz - you've really got a great grasp of the proportions concept. I find it amazing that so many people just go into body shape and don't take proportions into consideration.
To me there are a myriad of factors that will go into making your clothes work for you:
Body Shape
Body Proportions
Body shape side view
Scale (big bones, small bones etc)
Body variations (big or small bust, full upper arms, curvy calves or ankles, saddlebags, voluptuous tummy, flat bum, round bum.... the list goes on)
Texture, pattern and sheen
Personality
Colouring
There is no one factor that is more important - we are all a combination of ingredients and what makes our personal recipe work is our unique combination.
You are right - your body shape guidlines have to be discarded in places if they don't work for other aspects of your body - whether it's proportion or one of the other things I've listed above.
No one is more important really, and what we love and what we want to camouflage is something that is personal. That's why not all body shape information will work for you, parts will, parts won't.
I must write some more posts on these elements!