http://www.umbiumbiclub.com/
After a quick trip to Luanda, I was just looking at status on DT's Umbi Umbi Club and noticed that to attain Gold (the top tier) one must spend US$60,000 in 18 months - DT's program is based solely on spend, a model many other airlines are moving towards.
I am not sure about all programs but US$60,000 seems a heck of a lot of spend to attain top tier status on any airline, particuarly when you look at the benefits DT offers its elite.
I don't think EK's IO can be compared as it is not an official published tier level so I have just compared DT's Gold with EK Platinum, although I think DT's Gold is more akin to EK Gold. I achieve Gold on EK spending less than 1/6th of DT's spend requirement and could achieve EK Platinum for less than half of DT's requirement.
Of the programs I am familiar with and others that I have looked at, DT's seems by far the most difficult (ie, expensive and requiring the most amount of miles flown as a result) to obtain top tier status.
Are there any other programs out there that are harder to obtain top tier status on?