I recall them in their heyday. They were very well regarded at first, but rapidly seemed to wear a number of the components, especially the auxiliaries and the suspension.
As I understand it for the engines, there were Maybach in the Swindon-built locos and MAN in the North British ones (including the D63xx). The first few engines, D800-2 and D600-4/D6300-5 respectively) were built in Germany, the production batch were built in Britain, the Maybach ones by Bristol Siddeley in Coventry and the MAN ones by North British themselves in Glasgow. It was generally felt that, while under good conditions they were equal, the North British ones were poorer, particularly for the various auxiliaries NB had designed themselves rather than taking from the German design. The D63xx were particularly unreliable, far more so than their larger compatriots.
There was dissatisfaction at both ends about the North British locos; Swindon felt they should build them themselves and grudgingly sent the drawings (and possibly not quite all of them) to Glasgow, while the NB drawing office likewise felt out of a job and redrew to their own standards (which for diesels was not a lot) where they could, which led to the differences they ended up with.
I believe Maybach were taken over by Daimler-Benz (alias Mercedes) right in the middle of production being transferred, but it didn't cause much of an issue.
The German locos were apparently able to have their engines completely interchangeable, even to the extent of locos sometimes having one of each, but that didn't apply in Britain.
The German body was obviously too large for the UK loading gauge, and in redesigning it at Swindon for the UK gauge while keeping to the lightweight approach where the bodywork is an integral part of the structure many of the useful technical features of it were lost or minimised. That is why I doubt the German loco hulk featured above would be of structural value to any new build project. It's not an engine-and-body-on-heavy frame loco, like early diesel electrics, but a fully integral design.
The operational issue with Warships was their high speed riding. This was a combination of the downsizing of the loco from the German dimensions, and the notably higher speeds attained, for apparently the German locos even on express passenger work didn't get much above 100 km/h, that is 60 mph. They were more powerful that steam locos on the uphill (plenty of this in West Germany) but didn't get much faster on the downhill. They were good when brand new out of works, but the suspension etc parts wore rapidly. Their additional power had been used in Germany more to run heavier trains than to run faster. When they first came out on the Western they were run up to 100mph on Brunel's straights, such as on The Bristolian, but this was progressively cut back to 90 and then 80. Taunton enginemen, who handled them to both Paddington and Plymouth, said the worst was the gently curving descent from Savernake down to Newbury, where they were expected to run at full line speed, and the locos would be something of a bucking bronco. Going DOWN the South Devon banks was not so tightly timed, and some judicious use of the brake would help to steady the loco at the front.