My wife's latest car is an audi a4 tdi on a 59 plate. It's now done 10k on b100 with no dpf problems or indeed fuel filter changes.
Having said that the bulk of those miles are motorway work and the school run is across the Forest of Dean so mostly working miles.
To be honest I think if I was buying a newish car and only going to potter around in it. (This hurts me to say it!) I would probably go petrol and LPG it and run it until it dies!
That will be the reason you have not had Dpf regen.. I'm with you on the petrol Lpg route, the modern petrol engine is so economical and Lpg conversion loses next to no power these days too.
