If IKK and concierge are not valuable to you, I think you have your answer on whether to stretch to SE.

IKK - See the must-read threads at the top of the forum. If you are a business traveller, and you would like your spouse to travel with you in business class, this lets you immediately purchase the J fare using miles, without having to book 11 months in advance. A HUGE benefit for road warriors who travel to desirable destinations.

Concierge - Everything from schedule changes to seat assignments, these people make things happen (or so I've heard...)

7 day window vs 4 days (and day of departure priority) - Try using a SSWU as an SE versus an E on SYD/EZE routes, and see what difference it makes

Black card vs Brownish/Gold card - The deciding factor!