I've got 2 SC and don't use them from one year to the next.
The thing is.... I'm like miscella (apols if I've spelt that wrong), I'm what I call a pretty good cook (am shit at everything else) and if I have to thicken a casserole with cornflour, I've done something very wrong. The casserole goes a horrible milky colour when using cornflour and it tastes pasty.
I season and coat my beef with flour, then I caramelise it and that's the basis of beef in red wine or ale. Onions, mustards whatever added. At this point, I may as well just put it in my Le Creuset which honestly makes the most fab casseroles at 120degrees in my oven.
The caramelisation of the beef slowly releases the flour to thicken and darken the casserole and it tastes divine... usually 2 hours depending on size of cubed meat.
In the slow cooker, it is pale, insipid and watery and yes I half or quarter the liquid. It just doesn't have that rich taste you get from oven cooking.
So I think SC are great at mulled wine, soups (although I CBA to wait that long) or a chilli when you've got lots of people coming. But apart from that, no not really