I can't imagine it will raise the price. Frankly, the 75 frame never bothered me. Especially after I got a 75 Summilux 1.5 years ago. As it turns out though, I got rid of the lens recently and picked up a used a la carte 0.58 M7, with the 75 frame removed. I can't imagine trying to focus the 75 Summilux on a 0.58, not that I have the lens anymore, so it doesn't really bother me that it's gone. At the same time, it does remove the possibility of effectively using that focal length on this camera for me now. Which is ultimately fine, since a 28 will live on it most of the time. My specific thinking was this though: I want 0.58, and I don't plan on shooting 75 on this camera, so I'm indifferent to the 75 frame being there or not.
Long story short: I'd leave it if it doesn't bother you and I'd have it removed if YOU want it gone. Don't worry about sale prices.