Unfortunately it was my only first hand experience of the same marque for a comparison.
A Citroen BX GT isn't a 'classic' but I saw one sell out the back of a barn for £2900 recently, you tell me he would have got that much for it fifteen years ago?! When was the last time you remember calling a Citroen BX a classic.
I can debate until my death bed but I am safe in the knowledge that a good GT will turn a profit (if purchased for a sensible price).
I guess I won't find out for real until I sell my car!