The difference between E and SE is more than just more certs and IKK (although both are great on their own). 50% more tier bonus miles, concierge, SE line, selection of preferred seats on T+ fares, use of SE check-in line at airports such as YVR and unofficial perks such as more frequent up-ops, etc.

Last year I did not fly enough to requalify for SE, and this year I'll be lucky to get E again. I've already noticed a difference calling in (and not using the SE line, notwithstanding recent phone line problems). The big thing I miss is IKK as I've already tried booking reward flights and had very limited (or in some cases no) options.

SE is great, and IMHO much better than Elite. That being said, it is only worth it if you'll use the perks. It is highly unlikely that I'd go for 45k worth of mileage runs simply to reach that status level again.