I am not sure I understand your question? I am a developer and have sold a ton of top end homes in the South Slope. The price points are obviously less than Center Slope. Current trending on top end 2 family homes in the CS is over a $1,000 psf. The comps confirm this. The range is 750ish for nice and about 850 for well done and $1000 plus for super.
Good examples of South Slope homes with amenities like WBFs, etc., you might look at 303 13th Street; 158 14th Street, and 188 11th Street, for example. The South Slope homes are not at the crazy price point in the Center Slope. Again, the comps are dispositive.
A well done home in the South Slope is a very easy sale if it is priced right. I have never had problems in any of these locations. Of course, as a buyer or seller, you need to be smart, do your homework on possible projects coming your way, neighbors, etc. The number of no go blocks has gone from a lot in the mid to late 90s to virtually none now. PS - I have lived in PS for 30 years.
Condos are a totally different story and the pricing is completely different w/ completely different considerations.
I hope this helps. Good luck with your hunt.