This particular PS home is a new construction, with upgrade package. May not be worth much, but could be up to $50k. Also, this seems to be an Irvine Pacific Fiore home, so it tends to be overpriced. Even during down turn, they refuse to lower their prices.
Also, comparing the difference in prices with MR could lead to a bad financial decision.
The fact that GP is priced lower than OH/EW/PS means that its location is inferior to those 3 communities in the eyes of buyers. This means that, unless something drastically changes, GP will always be priced lower than OH/EW/PS. And that means that when you sell the homes, the difference will still be the same.
On the other hand, whatever difference you paid in MR is just dead money. You don't get it back.