I've got a 1.9 ref sport and it is really well specced. Standard mp3 and aux, tints, sports seats, elecrtic heated mirrors, alloys etc.
I routinely get 60 mpg on A roads (no traffic). The mpg is great and I have never got below 48mpg on mixed driving, even when comuting in traffic. The 1.9 is 105 bhp, but feels more powerful. It has loads of torque and pulls brilliantly.
Like you I wanted good mpg with a bit of zip, and the 1.9 gave me a great motor. I know the 1.9 is not as refined or powerful as the 2.0, but it is more than up to the job.
In fact in our opinion it is so good, we bought a touran as the main family car with the same engine and I've kept the Seat as the daily driver. We couldn't justify the extra money for the 2.0 litre Touran and the slightly lower mpg when the 1.9 engine is so strong. To give you a feel for overal power, we just went to Wales in the touran with 6 people (adults) with luggage and it pulled really well. No changing down up hills etc. On the 350 mile round trip we averaged 52.8mpg.
So good all round really.
What I would say is the 1.9 engine is very flexible. The reason I say this is that in the Seat it feels like the engine mapping is very different to the VW. The Seat is more sport orientated and aggressive, whereas the VW is longer legged and relaxed. Some of this will be down to the gearring, but some is definitely engine. So the engine can be mapped quite differently even in stock 105bhp form. With a revo etc I would think it would be really punchy, but not sure how this might effect mpg.
Overall a great engine with v.good mpg returns. It may sound a bit agricultural compared to new common rail engines, but it is great. Also as an added benefit the 1.9 engines do not have DPF's fitted so no worries about the dreaded DPF blockage and regeneration process.
Cheers
Al