I was in a similar position to you earlier in the year. I had a petrol 1.9 159 and it had a serious drink problem and I sold it to buy a 1.6 147. This was my third 147 (two 1.6's and a 2.0). After the 159 it felt light and agile and I loved the engine noise. It was a bit buzzy on the motorway but a lovely car. Anyway this summer went to Italy for a holiday and ended up having a diesel 1.9 159 as a hire car - completely by accident. This sort of reminded us just how much space there is in a 159, how comfortable it is and in diesel form quite economical yet punchy for accelerating. We came back got in the 147 at the airport 147 and it was a little bit of a disappointment. This was the first time this had ever happened to me: You go on holiday, have a hire car think hmmm... that was quite nice, get in your own car and think... No, that hire car was good but it's nowhere near as good as this. Anyway to cut a long story short I ended up buying a two year old 159 1.9JTDm lusso. This is a bit of a complete turn around for me because I've always been pretty scathing about things that use the black pump but it's really good, particularly when run on BP ultimate with millers eco sport. I'm sure a 200BHP remap would make it phenomenal. Anyway my wife has got a 1.6 147 as well and I still drive that every now and again and everytime I do I think it's good, but I prefer my car.
It is different I suppose a bit more grown up may be (marathon runner rather than sprinter??) I don't know about the 1.8 (I'd have a long long test drive to be sure and check the mpg) but the 159 is a great car. I doubt you'd be disappointed.
146 1.6TS, 156 2.0TS, 156 1.8TS, 147 1.6TS, 147 2.0TS, 159 1.9JTS, 147 1.6TS, 159 1.9JTDm, Mito 1.4, GT, Giulietta 2.0JTDm, Giulietta 1.4tb, Giulietta 1.6JTDm........