The DPF is discussed on a "local" forum, too. The first vehicles with it are now more than one year old. So far I haven´t seen someone writing about trouble with it on the Defender. There´s been one guy travelling 45k km´s with his Defender, up to mountains, to desert-like area, and no problems.
My garage (not that I´d expect serious answers from this one) says the DPF on the Defender appears troublefree to them.
Not that I do like the DPF on my 2.2, the 20k faultless km´s (concerning the DPF) may not proove very much I think, but I may care for other things on the rig first.
On the Defender2 forum I learnt that the latest ECU update (must be around for 1/2year now, deals with the regen.cycle happening too often. When my dealer updated (only upon request) the "oil service" message came on when starting the car (this after the update). This is rubbish in my case because oil was changed 5k km´s earlier. Ignore it. But it could have to do with the oil contamination and that the ECU update "wants" to have the oil changed, because it was assumed that there was Diesel in it due to bad regen.cycles and hence the update wanted by the customer.
Defender2 - View topic - Q225 - ENGINE CALIBRATION UPDATE
The vehicle with DPF needs engine oil with zero sulfur. IIRC the appendix to the viscosity is not A oder B, but C. "C1" to be precise. That is because sulfur burning will lead to gypsum and ash. And both of them do block the DPF but cannot be removed from it. The matter with sulfur applies to the fuel, too - I´d think

