DS is 21 months and has used a grobag since he was 6 months old. We have found it to be a godsend since he otherwise continuously kicks of his covers and wakes himself up. We bought a 1 tog gro bag last summer, but not until early June, and found we didn't get much use out of it as we bought it too late and he just had a light sheet over him.
Now, if he a sheet over him, he would play with his toes all night and crawl around his cot.
DH thinks it is a waste of money for a bit of sheet....
DS loves his grobag and smiles when he sees it in his cot.
Any positive/negative tales about the lightweight summer grobags? I am tempted to buy one anyway.....