I'm sure you have alot of sharp rocks there in Greece. But I can't imagine a more rocky place to ride than here in Southern Nevada. We have a type of lava rock here that is like the surface of a giant cheese grater, similar to broken coral. It will lacerate a leg and shred a tire's sidewall.
Have you considered also that on a hybrid bike about the max tire size available will be a 45 to 47c width. Which is only equal to a 1.8" to 1.9" mtb tire. Most mountain bikes run at least 2.1" to 2.3" width nowadays which does make a considerable difference in shock absorption and protection from rocks. A lot of people here in the western US run 2.4" or even 2.5" tires (at least in the front) just because of all the rocks. Even with a more serious fork on your hybrid you will still will be on relatively narrow tires for rocky terrain.
So I would just play to your hybrid bikes strength (faster and more nimble on pavement, dirt roads and smooth trails) and just take it a bit slower on the rough, rocky stuff.
It's always nice to know someone can feel your pain (when riding on rocks).
And nonetheless there is NOBODY in Greece riding those trails I do with a hybrid. In a way I feel like a pioneer!!!
__________________ 2010 Trek 3900 Disc in Matte Orange
So how many differant countries have you gone riding in/on?????? USA, Canada, Hawaii(oversea..lol), Qatar, Iraq and South Korea now.....more to follow though!
This is the bike upgraded, but it will not be like this for long... soon the fork will be replaced and the handlebar will become somewhat longer for imporoved control.