Yeah, sounds fairly accurate. I think all 170 TDi's will have the Diesel Particulate Filter and 140 TDi's froma certain age (possibly 2008 as you say) onwards.
The DPF is an expensive item and needs decent motorway useage from time to time to properly work (regen).
If the time comes and I get a car with a DPF fitted, I thin kone of my first mods would be to have it removed and coded out of the car's ECU. They also restrain your maximum potential gains on a remap.