8kg difference in the engines would be about right i reckon, but do we take the 1100 as 75kg as online says which makes the 750 67kg or do we use 95kg for the 750 which makes the 1100 103kg.
Your reasoning sounds right to me like. The weights I've seen for the 1100 do seem relatively light, just being on OSS lends some weight to the knowledge that's all.
Who knows eh!