Proto had so few differences compared with production models, mostly third magnet which doesn't change game play. Other things are just cosmetic. It doesn't have the proto clock (multicolor) so it appears to have been tinkered with. Add the amount of wear and I just don't see (Me personally) much extra value. Not sure many people find it different enough to warrant much more than $1-2k extra. I could be very wrong.
Give me a very nice production model without extra holes and plays the way they intended for 1/9 the price all day long.