I use one of those Pro Route yellow Carradice capes when the weather is wet and no wind - no wind is quite rare round here.
On a calm day it works really well as you ride along in a contained micro-climate, ventilated from the underneath, take it easy and you will stay dry.
Rain can be bouncing off the road and you will still be dry from the knees up. Of course you need a bike fitted with mudguards (fenders to some).
I also have the Carradice helmet cover but found it too small to use with a helmet having a peak. I now use a Vaude helmet cover which is a taped proofed nylon and quite waterproof. I have a choice of 3 colours, my sons having rejected the use of some.
Going slightly off topic, but still with a 'waxed' product…
When it is windy/wet I wear Paramo clothing.
Paramo is the most waterproof/breathable clothing I have encountered.
The only drawbacks are the high initial price and the warmth of the garments.
Paramo use a 'wash in' high tech wax to waterproof the cloth and a liner system which draws moisture outwards from your body.
I only use the Paramo trousers in dire conditions, too warm otherwise even with the vent zips open. Rainlegs
usually suffice to keep my knees and thighs dry and warm.