my ds is just like this, they are so similar!! ds is 19 months and although he walked at 11 months he has no sense of danger what-so-ever! I can climb on the sofa and does frequently. He doesn't want to sit on it like most children, he wants to climb on to the arms or the back and perch like a cat.... then has an enormoustantrum when I get him off or insist that he sits properly.
He could never go on a big slide or clibing frame, he'd fall off deffinitely. He can manage those slides at soft play centres though. We only started taking him a couple of months ago but has managed to master climbing up and sensibly coming down the slide on his tummy.
He is lethal around the house, running, climbing. One day last week me and dh found that he had climbed up the armchair, on to the back of it, clambered onto the window sill wehich is pretty high and was just stood there waving at the dog outside. I nearly had a heart attack.
He can't even be trusted on beds, he wriggles and rolls about and seems to have no idea where the edge of the bed is. I was wondering if this was normal too! He is just never still, always wriggling, climbing, running etc. I hear about kids of his age sat on the sofa watching entire episodes of In the Night Garden and I'm amazed, ds is just not into sitting still at all!!! He would rather risk his life to climb the book shelf instead .
That said, he is the sweetest, most affectionate little boy so i can't complain too much! He wears himself out that much in the day that he sleeps like a log for 12-13 hours a night so i am very lucky but he will be the death of me!