From a slotcar perspective the only advantage to using hypoid gears is that they are designed to work with the rear axle above the centerline of the motor shaft, which for a given sized rear tire will lower the cg.
Hypoid/bevelled gears were never really designed to be quieter, but rather they were designed for heavy industrial (high torque) applications where having the load spread across the entire face of the gear teeth was beneficial..........no slot car motors have that much torque, but, hypoid do have a place in slotcar racing due to the lowering of the cg. by raising the rear axle in relation to the motor shaft.
They are also designed with a specific "offset" in mind,.....the teeth on a Slot-it "offset" contrate are cut to work best with the rear axle 1mm above the motor shaft, excessive deviations in the "offset" amount will result in poor/noisy mesh.
So if your rear axle is level with the motor shaft (this only applies to inline motor configurations), and your gears are well installed, are in good shape, are close to ideal pitch (more on this in a moment) and the mesh is set correctly they will be whisper quiet.
As all of the plastic car manufacturers play silly bugger with their pinions and Spurs (in simple terms they alter the tooth shape to fit more/less teeth on a fixed diameter) it is good to know what is the ideal tooth count for any given diameter, as , if too many teeth are added/subtracted, mesh issues occur, as at a point, the pitch has to change.
So here is a "conversion thingie", that applies to all NSR/Slot-it/Scaleauto/MRSlotcar/Scaley gears.
Take the diameter of the gear and multiply by 2, then minus 2.
EG a 6.5mm pinion x 2 = 13 - 2 = 11T,..........for a 6.5mm diameter pinion an 11T is as close to .5 module as you will get,.....so "perfect" .5 module
EG a 18mm Slot-it spur x 2 = 36 - 2 = 34,........."perfect" pitch for an 18mm spur is 34T
You can deviate plus or minus 1T from "perfect" on a pinion without issues, and plus minus 2 teeth on a Spur before issues arise.
Hope this helps