“Right now, there is a ppsf differential of about 100 bucks between mission hills and North Park, but with substantially more variability ”

If you look at the sales prices and not list prices, I think things are tighter than that. I just took a look at redfin for zip codes 92103 and 92104 market trends for houses.

In 92104 the listing price for houses averages $397 a foot while the sold prices average $421 a foot. The sales to list price 98.13%.

Meanwhile, in 92103 the listing price for houses averages $514 a foot while the sold prices average $429 a foot. The sales to list price is 94.57%.

I realize that these are rough data and 92103 also includes Hillcrest, but the trend can be confirmed if you look at recent sales on a house per house basis. For whatever reason, the ppsf differential between 92103 and 92104 is collapsing for houses.