I bouth mine at Aldi - it's their Lumina brand. It's quite big, about 6L I think from memory. Would do a family of four no worries except that
DH is a BIG eater!

And I rarely fill it more than half full (shouldn't go above 2/3 full anyway). I find the oval shape cooks well and it's got the ceramic lift out bowl which you can serve from (is quite nice) and then chuck in the dishwasher, so very handy.
TBH, mine doesn't get the workout I planned for it, but that's because I'm not as organised as I'd like to be. I quite often have SC jags where I'll want to cook a couple of meals in a row in it, usually on weekends! Leftovers freeze well too.
I have no problems leaving mine on overnight or when I'm out of the house. Homemade baked beans for breakfast is a favourite around here