Would say it would depend on your 2.4 is it standard? I've driven both and own a 2.0jtd believe the mpg is slightly better on the 2.0, it's has far fewer DPF issues due to new close coupled design and EGR is also less troublesome. Seems to passively regen really well on dual carriageways n motorway runs. Rarely see the DPF light. If you decide it's too slow you can remap it to around the same power as your old 2.4, although if you think this may be an option youll want to check what gearbox is has (you want an F40 rather than M32) as they fitted a range to the 2.0jtd. Depending on spec things you might miss include - electronic seats? Q4? Second tail pipe? That five pot sound?
My 2.4 is currently mapped etc, and to be honest after having now driven the 2.0, I was pleasantly surprised by it....I was expecting to come away from it feeling extremely underwhelmed, but it really wasn't the case. Don't get me wrong, it is not as quick as the 2.4, and I knew it wasn't going to be especially with mine being mapped, but I was impressed. It pretty much felt very similar to what my 2.4 was like before the map. It's a little flat under 2000rpm, and 1st & 2nd gear I believe are torque limited (as they are also on the 2.4 in standard pre-map form) but once it gets going, it does feel quite lively with a smooth increasing power delivery right upto the redline, a little like driving a petrol. I often felt that the 2.4 seems to choke out at higher rpm, but is drastically improved with a good remap.
As you say, I've heard that they are meant to have less DPF and EGR issues, and to be honest this usually is a concern for me, as my work commute is a relatively short, city one which does not help and was the main reason for me having a remap and dpf removal on the 2.4.
I checked the gearbox, and although I couldn't actually see "F40" stamped on it, it did have the same selector/linkage setup as my 2.4 so I think it is safe to assume it does have an F40 box fitted, as the M32 selector is noticeably different as is the one on the Giulietta(forget model number "C" something)
Spec wise, my 2.4 is quite highly specced, I believe the only option missing was the sat nav(even has the rare tri-zone climate control and usually obsolete cd changer) but this 2.0 is also highly specced, which probably contributed to me falling for it.....it has the newer MY2011 interior with the red piping (which I love) and like mine is full electric along with dipping wing mirror(and folding) it HAS the sat nav(the later one with SD card, which really is nice and something I always wanted) it only has rear parking sensors, where as my 2.4 has front and rear with the function display(this I will miss, as I liked the display feature but can live without) mine isn't a Q4(I really wanted one of these!) both have xenons, which I think are a must!
Now the second tail pipe! YES this I will miss, along with the 5 pot sound! The 159 rear end was conceived to have twin tail pipes, and I will be sad to see this go....especially since mine has a alfatune stainless system! I so wish I had kept my standard exhaust!, but I'm not sure if this could even be fitted to the 2.0?
Thanks for your input Evo! Appreciated!