The T1 has a sliding cover in the front. also turns the cam on and off automatically.
i dont know much info on the t11, we wont really get to do a good comparison until it actually comes out, if it comes out in the US. It does have that new sport strap, and its thinner, how much thinner though? The T1 is barely an inch thick, ~0.8in, 21mm i believe.
Perhaps sony is having issues with the sliding cover? on an engineering perspective, i suppose its just one more part that can break, but who wouldnt want to protect that beautiful carl zeiss lens!