I've very often made it with red onions (or half and half red vs white/yellow). It's delicious and always been a success.
I've used a version of this recipe [0] which explicitly says "red or yellow onions". It's also honest on the cooking time. I'd agree with its main warning, that making your own nice stock from bones really improves the flavour. Doesn't have to be beef stock. But I've also used stock cubes in the past.
