I spoke at length with Dave Platt about his diesel experience. He grew up flying diesels (mostly Oliver/Tiger) in Great Britain and it is my impression he is/was quite well-versed in them. Back when he was competing at the highest levels of RC Scale, he was campaigning a T-28 in which he had installed a Moki 1.8 2 stroke glow. However, he wanted to spin a large 3 blade prop and also to have the engine fully enclosed and was worried about over-heating a regular glow engine under these conditions... So he converted the big Moki to diesel. In our conversation he told me he could never get the engine to run well enough to use in this application; he tried different fuel mixes and carburetion and finally gave up, converting back to glow.
It seems some engines just make bad diesel engines.
My experience has been that you probably cannot go wrong with a P.A.W.
They may not be the most modern powerplant, but they are designed from the ground up as diesels, and have many years of successful diesel experience behind their construction.
Picking the correct type of model and flying style is also integral to "success" with a diesel.