I can see that the H10 is better than the K4 in terms of serviceability. But I believe that intermediate shaft is still captive in the chassis. And the worm gear is still pressed onto the motor shaft. So when the motor fails, you'll have to find an exact replacement (or transfer the worm to another motor, which is very difficult to do.)
Also, there's nothing there to establish a precise mesh between the worm and worm wheel. Hopefully thrust bearings are incorporated in the gear end of the motor, but i doubt it. If the worm was pressed too far onto the motor shaft (or not far enough), there will be problems with the mesh. Adding shims would be tricky. Doing the opposite means removing material from the chassis with a file. Take a little too much out and you've ruined it!
In all fairness some lower-priced HO locos are made like the H10. But the best setup is a self-contained gearbox clamped around the worm wheel. A separate gearbox also facilitates changing gear ratios, as does the 3rd Rail setup with pulleys. So those of us who are willing to accept some motor noise in exchange for smoother performance can make that trade-off.
