To a degree these issues are common to all traditional daps just due to the nature of the design. Potentially this is why you haven't heard much critique of it from other khukuri folk. For it to clear the belly there needs to be space for the blade to move around inside. Unless the tip is purposely pointed down and away from the spine it will jab into the spine and stick. Rattling can be minimised with the a highly toleranced fit (particularly in the width of the throat) but if the sheath shrinks due to getting wet and drying/ slightly green materials then your sheath can become very difficult to use. With this said,
M
meboz
is right- the traditional daps arent't too bulky and are our second lightest option. K and C does add a bit of width. They carry nicely, particularly for blades in the 9"-15" range and are quite smart looking. Smaller blades can need a bit more retention from the sheath and match a lower profile well. Bigger blades tend to benefit from easier drawing and carry options.
We tend to suggest either stacked leather or kydex for those looking for hard working blades due to ease of use, durability and carry options. The kydex is easy to sheath or unsheath and we can add secondary retention through a spine lock or strap if required. For me I prefer western leather in most situations. It is quieter and softer in the hand which can give a more tranquil time in the woods. It also has most of the same carry options as kydex without the complexity of form that comes with modularity. I like that simplicity, but also don't ever need to lash a sheath to a pack or clip to molle webbing so am not losing out on much.
Take care,
Andrew and the team at Kailash