I do think they are actually quite heavy,but I do feel its a comfortable trade off for me,as they get slung about round parks,cars,paths (really) I like the leather as its so robust and I don't worry about it tearing or ripping. I do really stuff them full of stuff too,as Sophie does'nt have her own entourage I have to carry everything!!!
And yes it makes the roxy or elgin super heavy!! But I have been hauling a toddler about for a while now and I have to say my arms,shoulders and back are the best shape they have ever been in!! So the bags although heavy for some(my freinds think I have got the strength of a navvy now!),are'nt too bad to me,I think its a case of what you get used to.
When I first had the Blenheim and needed to carry paperwork and stuff,I did get a Burberry shopper,and its handle meant there was no chance of overloading my shoulders,maybe a Helier from an outlet would be good to distribute the weight a bit,and its a good excuse to get another bag!!!