Your Hi Power is drop dead gorgeous. If it were mine I wouldn't let it get away. I've always been attracted to the shiny guns and this is all that and more. It is an unusual BHP. These don't come around that often. The condition looks very nice too. I'm in the camp that says KEEP IT!!! As you become more knowledgable about guns you'll kick yourself if you don't....GUARANTEED. Also there are some people that say FN(manufacturers of this gun)are phasing them out. The .40 is no longer made and the 9 may become a casualty soon too, from what I've heard.
How rare are they? Can you quote production numbers? Certainly they made less of them then then say a standard blued BHP but they are not that unusual.
Since the OP states he has big hands without modification this gun will never be a good shooter for him. I am willing to bet if he grips the pistol properly he will be one those who suffer BHP hammer bite.
As for the BHP going away. That is not going to happen. People have been saying that for 10 years and they keep building them. They do limit the number produced but that is a much about increasing demand as anything else. They are considered a hi end gun so they keep the production at a level which maintains that.