overall it would also depend on the width of your strings and size of the blocks. 2.5" strings on a 12" block will give a much different weight than using string strings
my strings are 3/4-1-1/4" wide and 6" would be the largest block I'd make. Total weight is one of the reasons I don't use any leave in base but use papers. And I make sure there are seldom any seams coming into corners.
that said I've made a couple of double sided string quilts with no batt and been very happy with them.