Appreciation or depreciation is just a factor of availability and desirability.
The water cooled models have been made in vastly larger numbers than their air cooled brethren. However the water cooler but limited models (gt3 gt2 etc) have all held or appreciated over time and will be collectible.
I love my 76 lux with an updated 3.0sc engine. It's light, narrow challenging to drive and consequently fun. On the downside I may be reaching the end of my tenure with it as it just won't fit 2 small children and me in it. Despite what I told my wife when I bought it....
