The weight of a lithium polymer (LiPo) battery is determined by various factors such as its capacity, number of cells, and the materials used in its construction. However, in general, it's reasonable to assume that a 1600 mAh 2S LiPo battery would weigh more than an 800 mAh 2S LiPo battery, as it has a higher capacity and hence, more energy stored in it.

As for the exact weight of an 800 or 1600 2S LiPo battery with an XT60 connector, it would depend on the specific brand and model of the battery. However, a quick online search shows that on average, an 800 mAh 2S LiPo battery with an XT60 connector weighs around 45-55 grams, while a 1600 mAh 2S LiPo battery with an XT60 connector weighs around 80-100 grams.