DPFs. More hassle than they're worth?

Likely to be a faulty pressure sensor - common on VAG group cars. Find the faulty sensor, replace and do a force regen and should hopefully be good.

I would guess a faulty pressure sensor, get yourself the VAG DPF app on android and a ELM327 bluetooth reader / dongle "vgate" ones work well, on the app you have to select the correct engine code, it will tell you everything happening on an active dpf regen, yes on VAG cars they will regen at 1500 rpm, even on idle, because it's the temperature of the DPF that matters, when it hits over 600c the regen will happen quickly, it does this by adding extra diesel called post injection, when you can also see grey smoke when you stop, passive regen happens under certain parameters, usually on a dual carriageway. (They will also regen pootling around town, you'll see the smoke when you stop and set off again)

Thrashing it will be counter productive to a regen, because it will slow it down, or it will stop, or lifting your foot off the throttle, on a VAG common rail tdi, the best method I've discovered after doing 100's is 4th gear at about 60 mph the rpm's will be about 2000 to 2200, you can thrash it a little to get it hotter, then aim for a hill at that speed, once it hits 600 plus c on the dpf the regen happens quickly, probably 10-12 mins.

It's not a brilliant idea to switch them off during an active regen because of the increased risk of fuel dilution, people do that everyday.

Those codes are just telling you that it's blocking up, a restriction is happening, I'm guessing you have the exhaust symbol dpf light on the dashboard, that's the last stage before it'll go into limp mode and you'll be in a vw garage. Your best bet is to get it to a trusted VAG specialist with the correct equipment, they'll be looking at the differential pressure etc, basically it's not working because of a fault, the easiest one to change is the pressure sensor, it's the plastic rectangular shaped thing with a pipe to nowhere, assuming it's the same on a 3.0 tdi. There's a point whereby it won't regen without specialist equipment as a safety measure, not sure if 31 grams is there or not.

You need to get it to a VAG specialist who know the car, personally not keen on the mobile DPF specialists, when it's working, they can perform a forced regen with their equipment. Throwing in a can of archoil AR6400-D will help clear it when it's fixed, it won't solve anything.