not sure what kind of triails/gravel roads ya want to ride but i think they would both suck for that purpose. they are under powered. fun at first on the street then the bordom kicks in because htey aren't powerful enough.
are you looking at buying new? what are they? 2900-4300ish? i think i'd spend now and just buy a small dual sport . i think it would be a better all around bike for what you are doing...
jamie and i have kawisaki z125's. they were fun for what we wanted them for in the begining. boring now.. just not enough power. i can get them to 54mph but they just aren't cutting it any more.. we will probably sell them and buy a dual sport. it will do more things that we like and do them better.
my daughter has a klx140. fun little bike. not street legal though and while the suspension is fine for her at 100 pounds its not enough for my 190 lbs..