Is it worth training my PG/SGs in the C catagory to get there IS off 1 (atrocious)?
It depends on many things:
Your players potential, age and height, his skillset, and your plans.
For example, if you have an 18 year old HOF. his height is 6'7 and most of his skills are average and respectable, then yes, it is worth.
But if you have a monoskill perennial-allstar with isn't very tall... Then that's a big no:)