Referring to your second paragraph,
I have been thinking about this as well,as mine should really be replaced,being a company vehicle,but we haven't done many k's,and we love it.And it is sorted how we want it,17" rims,etc.
The D4 is very well tried and tested,and a fantastic vehicle.It has evolved very well,been improved in many areas,and is way ahead of anything else in its class,and extremely reliable.
The D5 is unknown.A bit like the new Defender
 
I never buy the first of any model,whatever brand,so i wouldn't buy a D5 for a year or two.
The other thing is resale,in say 5 yrs time,a D5 will be worth a lot more than a D4,although a D5 will probably cost more.
Bottom line,i will more than likely hang on to the D4 i have Just my 2cents worth
Just my 2cents worth
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