Over here in Australia we have had the older style combined DPF/Cat since late 2007 on a few cars, but my direct experience is the 170hp BMN engine. Seems DPF's clog quickly due to the situations you mention above, basically down to soot production / off boost situations, where the isn't enough air for the fuel injected via the accelerator pedal. Inner city driving is the biggest killer, and it actually takes some pretty aggressive driving to get the DPF towards anything like DPF passive regen temps from my experiments.
I have heard of a few DPF's clogging terminally around 100k, but VW tell me they should last 150k. I put a Provent on my TDI from new, and have since hobbled the EGR, both of which contribute to DPF clogging. VW themselves state in their manuals that oil ash cannot be regenerated, and eventually builds up in the DPF, so oil quality, blowby quantity and overall engine condition are important factors there. Certainly running the engine in hard to bed the rings as best you can is important to reduce overall blowby.
EGR lowers combustion temps to drop NOX production, but in turn reduces available O2, adding to soot production. Certainly since hobbling my EGR, and making a lot of mods to both lower the temps and increase the flow, my DPF actively regenerates a lot less.
In my mind the DPF needs to be kept as hot as possible, and some sort of thermal wrap / coating would only be beneficial there. Someone needs to produce an electric blanket concept, where you can actively bake your DPF, and get the temps into the range where passive regen starts to happen.
An EGT gauge coupled with a boost gauge are powerful tools to learn how to drive to avoid soot, and to get the DPF temps up when it's possible and legal to do so, such as up a long hill.
I do see the new split DPF in the MK6 as a good step forward, and hopefully a reduced cost when they eventually clog, which should be a lot longer with common rail, DPF and PD were never designed to work together, common rail will definately produce less soot overall.
The car will throw a forced "active" regen at about 40% blocked, the DPF light comes up if this fails and it approaches 50%, and the coil light joins the fray at 60% blocked plus. I've tried all those steps by turning regens off to see what happened. Apparently the car goes into limp and wonlt actively run after 80% blocked, and this process would happen within 2 months of normal driving without regens in my approximation.