A properly working D-jet system is hard to beat. Volvo said as much with an ad introducing the 1800E in 1970, which showed a pair of DCOE Webers with the caption "It goes faster without them"

I once converted a 72 145E to a single Weber (DGV) due to mysterious problems I couldn't figure out at the time (in hindsight, probably due to a failing fuel pressure regulator) and regretted it ever after. The only thing a single Weber is better than is Strombergs. While SUs can be quite satisfactory when set up correctly (impossible if they are worn out) they are not as good as fuel injection.

In my experience, (well over 100K miles in 3 different D-jet cars) problems with the injectors are rare--I don't think I ever had to replace one. The throttle switch can cause trouble, the auxiliary air valve rarely works correctly, and I've seen a MAP sensor go bad once or twice, but most problems are caused by the wiring harness and the crimped on terminals that connect to all of the various components. Either they corrode or the wires fray due to vibration, resulting in weak or intermittent connections. Still, I recommend keeping the injection if it is at all practical to do so.