Egapal I deeply respect you approach and opinions. I believe firmly that debate will increase depth and understanding of a given situation or lesson. I teach in a university as well as manage a mac computer lab. I get where you perspective and how your background influences your statements. (have your re-started it? )

The original question of slightly arboreal I think we are agreeing has been answered there is ground evidence to support that. Moving on, I don't like using terms like happiness as I am not sure it can be applied. If we say over all heath and stress free I think that can be applied. Do they need to climb no I don't believe so, is there benefit to sacrificing floor space to branches or other *SECURE* climbing items?

The benefits as I see then that if the snake chooses to climb or not it provides over head cover, as anyone whom has dealt with ball pythons many (I think I can say most here) will react quickly to a shadow or object passed over their heads. Most long term captives have shorter lived reactions than young Royals but most will have some reaction. A jerk or stop or a complete withdrawal and coil over the head. Having a static object to provide cover seems to have a calming effect. This is the base principal behind a rack as well a large low over head object.

The second as you mentioned a climbing snake is working muscles and that aids in digestion when not being handled regularly. The regular handling of some snakes causes them stress and that can lead to bigger issues down the road.

The last point I'd make is hard to qualify with any kind of evidence. I have been trying something just out of curiosity, I have 9 Royal Pythons 3 in a rack, one in a screen top tank, one in a side converted tank and 3 in custom snake enclosures. I have been rotating every 8 months or so the 3 from the rack to enclosures and vice versa. Given some time to adjust to the new enclosure (a week or so) they all start to eat and adjust. The interesting part is there seems to be a personality shift. I have been using my most timid and most boisterous and one that is average. All of them seem to alter in the enclosure with lots of cover and stuff to explore. They across the board become less timid (most apparent with my really timid girl) and more attuned to what is going on around them. If I change the water in the enclosure they will often come out sometime that evening and check what is different quite carefully. The rack snakes hide, the only time they make an appearance (looking into the tub) is the night before feeding day and the night of feeding day. The others will often be seen head out of the hide in the late evenings most of the week but for a day or two after feeding day.

It is hard to document that shift and it is not a large enough cross section to be definitive for sure and it also has not been near enough time but it is interesting results so far. Does that mean they are more or less healthy NO NOT AT ALL!!! it just means that in a more naturalistic enclosure I have observed a wider range of behaviour than I observe in a rack. I know that Philippe De Vosjoli in 'The Art of Keeping Snakes' suggests that he has also observed something similar.

There can be benefits to providing climbs and 'sky' cover, and at this point I have not seen any points against providing a climbing opportunity that is beyond they can't climb, or they are really poor climbers and will fall and hurt them selves. I have never encountered a snake that hurt itself from falling in its own enclosure, from unsecured items falling on the snake yes from dropped snakes also yes from falling off a desk or something quite high yes but not from within a enclosure typically seem housing Royal pythons (12-18 inches high)

SECURE CLIMBS ones that WILL NOT FALL. Is very important here, if you cannot secure a climbing structure it should not be there.