i usually carry a saw as well, however im quite the opposite - id rather just hack something down/apart with a chopper than saw at it. in a survival situation, where energy expenditure becomes a very serious consideration, i would try to do the opposite. however, getting into one of these situations is rare. most of the time i relish the bit of extra workout.
that said, for an ideal survival setup where weight was a huge issue i would carry a gerber folding gator saw and an extra blade - cheap, light, cuts like crazy. an SAK, and a light sharp knife with dimensions like the mora. in my survival kit amongst the other things i have a good quality wire saw which would handle anything too thick for the gerber.
however, for camping i dont mind carrying the extra 18-22 ounces of a becker BK-9 or a brute. even for a survival situation i would feel a lot more comfortable with it strapped to my thigh or pack strap than without it. if the weight becomes such a horrible issue i can always
choose to leave it at the shelter. but its there if i need it.
a big, sturdy knife like the BK-9 or brute (these are made of 1/4" thick carbon steel) makes a very versatile, durable tool. it can be adapted to many different uses that come up with less fear of damaging it - if you bring only a mora and break it you are in big trouble, there are many things you can do with a large knife that you just cannnot do with a small flexible knife like a mora.
so yeah, if i am carrying something like the brute and find myself in a survival situation, the last thing id say to myself is
'damn, why did i bring this bulky thing, i should have left it at home'. in a normal non-survival camping setting an extra 10-12 ounces over the mora isnt going to break you - if it does then you need to eat some more big macs

in ultralight camping, you might say that something like the brute is too heavy. ironically, many ultralight campers carry only a small tarp and construct their own shelters, in which case something that can chop/delimb/sharpen stakes efficiently is a must. many carry folding saws, tomahawks/hatchets and mid-large sized fixed blades.
in short, id always rather have a large knife with me and have the option of using it. if necessary, i can always leave it at camp, in the trunk, etc but its there if i need it. a mora is only $12-15, no reason why you cant pick up something light like that as well.
cheers,
-gabriel