We got one for each bedroom in the summer, the 4.5 tog. Loved them so much have just got the warmer ones. Also got one for my mum as she struggles with duvet covers
Would really recommend. They dry great and you can tumble dry them and the insides don't ball up.
We don't find the 10.5 tog warm enough so we supplement with a throw and considering using the thinner summer one as a top sheet for really cold nights.