There is not much between the different drugs - dabigatran cant be used in renal failure and a few other issues. I suspect most doctors stick to one or the other. Of course only a few patients are on permanent anticoagulation - mostly patients with atrial fibrillation. The vast majority are on for 1-3 months.
The CAA website says no ticket for 6 months due to INR stabilisation on warfarin - interesting as I would expect to have a patient stable in 6 weeks - and 3 months for the newer drugs to ensure there are no side effects. Not sure I follow the logic as side effects are usually seen in days. They may mean in case there is a bleed, but perhaps they are just being ultra cautious - new drug syndrome. Would be interested to hear from others