The engines aren't bad at all - I switched from a 300bhp 350z to a Leon TDi FR and was reluctant to do so initially. Although it's amazingly cheaper to run/insure/tax, I couldn't
help referring to the 'on paper stats' and how I'd be losing 3 seconds from 0-60.
I admit that the low end torque compared to the 350 is not on the same planet (but it's a completely different animal and shouldn't be compared), but once you hit the turbo range, it's a complete beast!
The DPF issue with the FR is a good reason to to take the standard 2.0 TDi but this largley depends on the mileage you'll be putting in and how much of that is on the open road (ie motorway). It only took a week of town driving to trigger the dpf warning light (and soon after limp mode) on mine.
The 140ps will easily remap to the 170ps of the FR for about £300 and you can avoid any issues with the DPF.
Or, if you have around £800 left in your budget, you could have the DPF bypassed and mapped to around 220-240Bhp - not bad for a diesel!
I haven't heard of any serious reliability issues either - these forums are the best place to spot issues and evaluate your choice before purchase.
All in all, it's a fine car.