4 speed conversion. Help or hurt value of car?

I am on the other side of the spectrum ....I would say it would help.

I have changed every automatic car I have to manual shift and when I buy cars the first thing I look for is a third pedal.

if I were to spend big hard earned money on a car it would have to be a 4 speed or I would walk away.

keep in mind that 4 speed conversions are expensive, there is nothing cheap about anything 4 speed.
I agree. If you had a rare (and all matching numbers) 69 440 M code Cuda, big block Dart or a Formula S car, I would say leave it with the auto IF you are concerned with value. Otherwise, put a 4 speed in it. I truly believe that an authentic 4 speed conversion will increase your car's value. If a person really wants a 4 speed, they are not real easy to find. Most are autos. If you measure and cut the hump out carefully, you could weld it back in so as to be unnoticeable. Plus, save everything else (unless you have to sell it to finance the swap), and you could put it back to an auto. Bottom line is this; If you want a four speed, do it! I did it in my 1969 Barracuda, and I do not regret it at all.