You can't really compare an old style mechanically injected engine to a direct injection with a VNT turbo,it's two completely different generations of technology,if people on here are going to be throwing a mitsubishi diesel into their car its going to be a mechanically injected one,otherwise it would cost a fortune and be nothing short of a PITA to get it to work properly.
The mechanically injected 4d56 was a fairly bad move in the Mk2,mitsubishi had to gear them so low that at 100Km/h they are pretty much out of their power band same goes for the Hyundai galloper,and if you gear them a bit higher they cruise better but get upset by hills. They were mainly aimed at farmers that would probably just be tipping about towing stuff.
You can tune a 4d56's pump and boost and it will be way more drivable,but it has to be on boost to use the extra power,which makes it thirsty,however it would give a standard 4m40 paj a bit of a fright,however i've done the same to mine,and a few other small things,and it is enough to give a 03 3.2 did a fair run for it's money,However by doing all this you're working it harder,and increasing the chances of blowing it up.
I'll give the devil it's due,the 2.5 in the new L200 is quite nice,it doesn't seem like the same engine at all really,but it isn't exactly going to drop straight into a mk2,same goes for the new pajero though,took a 09 for a spin a small while ago and it was great,and TBH was better set up for drivability than the L200
But what I don't get is people wanting to replace a nice v6 petrol engine for a diesel engine,it's a step back in most cases. The 2.5 engine doesn't sound too much like a tractor when it idles,but if you compare it to the V6 it is very agricultural. The 2.8 idles louder but once it is driving the noise isn't as intrusive,but the 2.5 is screaming at anything over 2000RPM,meanwhile in a V6 you can drown out the noise from the engine with the heater blower! The diesel pajeros are more of a work vehicle they can tow pretty well and run on anything,but there is no real reason to go out of your way to have a diesel engine when you already have a petrol engine