Nice write up.My experience with my Leon FR ST 184 is very positive. No car is perfect but for me I think it ticks the most boxes for my budget.
Cheap to run - £30 tax and I get 55-60 mpg on my commute to work at 25 miles each way which I would say is mixed driving with traffic and A roads. (Have seen 70mpg on a few gentle journeys)
Pulls like a train, feels like a powerful engine in a light body. It's no race car - but for an everyday commuter I would struggle to justify more power/torque per weight.
Big boot. (bigger than my previous Audi A4 B6 Avant)
Drives nice, slightly lacking steering feel and brakes are a little too assisted for my liking (but that's similar to most modern cars) and you get used to it.
Looks nice (to my eye - and it's growing on me) LED rear lights look ace, only ones which look better to me are the Volvo V60 rear lights.
I don't really notice DPF regens - seems to be about once a tank full. Sometimes when I stop the engine fans are whirring away (wish there was an idiot light telling you it was doing a regen) I normally do approx 600 miles to a tank which I think is arround £50/55 (from memory as now i'm mainly working from home i'm filling up very infrequently) By all accounts the DPF system is reliable - well as reliable as a DPF can be!
Only problem I have had is the heater matrix issue which is well documented on here - which could be expensive if you can't fix it your self, and i'm probably due some rear shocks at 95,000 miles (oil misting). Just done my timing belt which Diesels need at 5 years.
The 184 does have more than just a more powerful engine over the 150. Bigger brakes, better rear suspension (independent vs beam) bigger diameter dampers, bigger turbo, stronger clutch, alloy suspension knuckles (vs iron). For me and the 150 and 184 I was getting insurance quotes with less than a £5 difference! so it was a no-brainer.
Can't comment on the 1.4 tsi, except to say my parents-in-law have this engine in their TRoc and it seems very smooth and refined. They get 40-45mpg but only doing very short trips to work.
When I was looking for my next car (a couple of years ago) the only cars which came close to the Leon were the 320D touring and Volvo V60 D5, which were both more expensive and considerably smaller boots, and the BMW can have expensive timing chain issues. Glad I got the Leon looking back on my choice. The Leon is also 200 - 300kg lighter than those two! I would have had a golf GTD estate but the prices for those were crazy!
Ref the DPF regen `light` - I would seriously recommend the Carista OBD dongle and VAG DPF app. You can then either have a quick look to see how close the car is to a regen or actually monitor it in real time to see when it's doing one and make sure it's finished and cooled down before you turn it off. Now I'm working from home, doing shorter journeys and gone from 22,000 miles to about 5,000 miles, it's really useful to have.