I have 10 GPs in my humble collection. 3 SH IIs. the John Harrison in hobnail and the SH II both in grey and black dial...
Being a watch enthusiast, I find GP watches a very collectable item, they make very good and refine cases, the in hse movement is in a class of its own and not forgetting the pleasure of wearing a watch with alot of history behind it.
production numbers are small too and thats makes it even better 
Get a GP!
Cheers,
ed