I disagree that the flexi has an advantage over the Bendi because it has front wheel drive. The Bendi is available in front wheel drive too as well as rear wheel drive and four wheel drive. Also, 50% of an articulated truck's stacking time is done in reverse by the very nature of the design so when does rear wheel become front wheel drive? The drive system is dictated by the application: Front wheel drive costs less but there is less traction so it's a trade off. All the articulated trucks require the centre of gravity to be at the broader rear of the truck leaving the front relatively light. Rear wheel drive offers much better traction.
However I agree that the productivity figures of all articulated trucks is more often than not 50-60% above that of a reach truck.