My tip for buying a TD5 is be prepaired to spend a few quid on it cause they do go wrong. ( the anount will depend on how well the vehicle has been looked after in the past and how good you are with the spanners ).
This is the same for ALL modern motors without warranty.
I,ve had a good experience with my TD5 Disco, and my brother has had a pretty faultless run with his TD5 90.
I,d be surprised to see a TD5 Disco, late or otherwise, that had,nt had new fuel pump,fuel pressure regulator,slave and master clutch cylinders,starter motor cotacts, air bags and height sensors and leaky sunroofs. ACE pipes are also known for corrosion.
The 200 and 300 TDi,s are great engine,s, but those cars are getting on now, and I can see why people want something a bit newer.
If it was just a Defender that you want then perhaps the engine stands out on its own a bit more.
I dont think theres a " wrong and right " to choosing.
Your doing the right thing by researching before you buy, and hopefully your findings will help you decide, and put you in the picture about these vehicles.
Del.