1K has value if you can use the PlusPoints. For me, I fail to get the UG with PPs applied 50% of the time internationally (even after buying P+ to improve my chances). Domestically, I've gotten zero PP UGs in the last 3 years now. On DL (as a Plat), I have a 100% success rate, using RUCs, finding advance UG space-this for long haul domestic, transcon itineraries.

The value of knowing that you are in PZ in advance is significant so, absent a big increase in advance PZ space, I wouldn't even spend an extra 1K to get 1K. 6K gets me a RT to Asia in J on another carrier, so I'd rather spend my money on a guaranteed J seat than chasing status so I can get more PP lottery tickets.