Hi I have recently made this kit of the DH9 Ambulance version, for a doctor friend as it happens.
I'm pleased with the result, now I've 'signed it off' - what you see has a nice acrylic case over the top, and I've found that that simple if pricey addition makes a model look suddenly brilliant

Yes, I had problems: some I should have avoided by merely being more patient with glue setting or paint drying etc. The decals weren't made of the best material - I've had better from Roden - and the roundels were particularly tricky. I suppose the main unexpected difficulty arose from the large cutout in the lower starboard wing. Overall the wings being moulded in one piece is good, but that cutout made for a lot of flexing which in the end led to some lopsidedness and floppiness on certain wires. Apart from that, and a few mishaps during a very protracted rigging process, I didn't mind the rigging. I did wonder about Geoffrey de Havilland's evident lack of interest in reducing the huge amount of wiring festooning his designs.
Oh, and I was cursing the Roden artist's skills at one point. At first I thought he(?)'d been a bit gung-ho with some of the details he'd included in the box top painting, but when I looked very closely at the Datafile photo which he'd based it on, I saw that he had accurately spotted several extra bits of cabling which don't appear on the standard plans. Hence why I fitted wires on the rear undercarriage legs as well as the front ones.
Anyway - not perfect(!), but as a middling modeller, I was pleased with this.
Cheers, Mark
PS - I've never seen a kit with so many redundant parts before. There are no less than
three unused fuselage tops! The box still looks pretty packed even though I've finished.