I've only ever driven my 2.4 159, but I do have a 3.2 GT, so can tell you what my check list would be.
Do I mind the sound of a diesel? Not keen, never again.
Do I do a lot of miles? No
Do I want tons of power? Remap if diesel
Do I drive it around town a lot? Yep, Q-tronic and petrol
Am I worried about weight of front end? Good alignment or TBI
I have a full on love/hate with my 159, didn't like it yesterday, but Wife drove past me in town this morning and I heard the Wizard exhaust, never heard it from outside apart from on the driveway. Sounded brilliant, so for most of today I've just been thrashing it around with the windows down and absolutely loving it.
It's always nice when after a long journey, you still have fuel in the tank, but in hindsight and knowing that my road tax is now paid monthly a V6 should've been my choice. At the time I bought my 159 I didn't fancy 2 higher tax band cars, couldn't afford a TBI TI, but still wanted tons of poke, so went for the 2.4. To make my 2.4 very good, I've spent a hell of a lot on it, so unless I'd have bought a faulty V6, a V6 would've worked out much cheaper, sounded great and no turbos to go wrong.
I would like to know how much lighter a TBI feels at the front and it's got plenty of poke, it's just that my old 1.8 156 didn't sound chunky enough and I hear the TBI is lack lustre on the noise front. So that'd be something I'd have to try and sort.
If you get a 159, get it aligned otherwise it'll likely feel very front heavy. There's a thread on here with correct settings, but you may have to plead with the Garage to make the settings.
GT 3.2 V6 - Q2, KONI FSD & EIBACH PROKIT, GTA REMAP, MICHELLIN PS3's, BMC CDA
159 SW 2.4JTDM TI - ALFATUNED, WIZARD BACK BOXES, KW V3 COILOVERS, NOKIAN WR A3/MICHELLIN PS3, PCA DYNAMICS ALIGNMENT.