very true a few grams are not a big deal at hall however 100g is actually about 1/4lb, so 150 per wheel is 300g or almost 3/4 of a pound, Maybe that matters to you maybe it doesn't, but either way that the difference, for the op thats not as big of a deal, as those wheels had smaller weight diffs (although the xt/717 is prolly like 200+g heavier than the crosstrail? idk don't have the weights in front of me)
I will say that it does add up, for example xt 6 bolt vs xt centerlock (756 vs 775) 80g for each hub if i remember correctly, now lets say the xt717vs somthin a tad heavier 117 for the sake of arguments, thats 50g per wheel, now we are at 260g diff in the wheelsets, lets add butted vs nonbutted spokes thats about another 60g diff, so 320 now (or 3/4lb) but thats just the wheels, xc vs all mountain tires this post vs that post ect ect ect, all of the sudden a few grams hear or a few grams there was 2-3lbs
My bike is currently 30lbs I just wanna say i'm not countin every gram, i'm just a gear geek lol