If you order today you will get it in May. So the difference is 1 or 2 months. Why dont you rent a car while you wait? Well, it also depends on whether the changes are important to you. For the 50i, the biggest change with the new model is the new 8 speed gearbox. It changes much faster and thus also has a much quicker 0-60 time as compared to the current X6.

New options also will be Active cruise control with Stop and Go (current model has only STOP), and Side View options.

your call.