The 1.9JTD is a lighter engine and therefore, some people say better balanced on the handling side of things. It's pretty much the same engine, just a cylinder less than the 20v. You can re-map the 1.9 to about 190bhp normally with the 2.4 being mapped to around 220bhp or so. The only real downside to doing this on the 2.4 is that the remap speeds up the wearing process on the driveshafts which are already a weakspot on the car. So you could end up spending money on an almost regular basis replacing driveshafts if you are not careful.
The other thing to also consider if you're going to remap the car on purchase is upgrading the brakes at the same time. It's worth investing in some performance pads to ensure you can stop the car properly with the extra Power.
The best thing to do is go and drive both and see what you think. Both will improve with roughly the same increases after mapping, so it's personal preference really.