Have you ever considered putting him in a swimming course at your local ymca. That worked to my daughters benefit years ago when she was a toddler. It is a sensory issue. Swimming is Occupation Therapy and Socialization all wrapped into one! The motions in the water, water going in one ear and out the other as well as the breeze his body feels as he's diving off the diving board will release excessive sensory skills and help with toning him down.
Another thing that would help toning him down is using essential oil on him as well as having him soak for 20 mins in lavender Epson salt. As it absorbs in his body the magnesium relaxes him, and sulfate tones down nerves. Throw some lavender essential oil in the water, but then after he gets out put about 5 drops of the oil on his spinal cord. LOTS of nerves there. Very soothing and relaxing!

I bought the plastic balls and added them to the trampoline he had with the net on, made him a ball pit they might be easier to keep in the trampoline with him then balloons. My son love's balloons, but the thing about him and balloons it that I know a meltdown is going to happen in the end because, it either it floats off or pops not good either way.So I try to avoid balloons as much as possible :). Now as far as discipline I do Kayden, I know when he's just be a little butt and when he is really have trouble with things, the are kids and so act up. I know there was one time Me, Kayden, mom and my sister was at a restaurant he started throw spoons of beans at my mom and laughing. I know he was acting out, I would try to set him down but he wasn't hearing it, then as you know the looks from all them perfect parents that never had a child act up in public was looking at me lol by that point I'd had enough I pop that bottom ( not hard just enough to get his attention) and told him he better stop throw beans and act right. you should have seen the look on them people face's, that when I spook load enough for all of them to hear me and said "He is more then welcome to eat at anyone's table if they want" everyone looked down at there food and didn't look no more..lol but the point is he set down for the rest of the meal so I know he understood what he was doing I think he was testing to see how far he could go and everyone has to have a limit regardless.like you said safety they could get hurt. But I've also learn to pick my battles I know sometime I will try to distract him with something else that he likes better. I think Kayden loves jumping off the back of my moms couch is hes just bored his mind is going 90 mph all day nonstop he has to keep doing something at all time. so maybe try to drawn into something else get his mind focused elsewhere. would love to know how it works out with the trampoline let me know. have a great day..

I would speak with his occupational therapist about discipline. They will know best.

The toddler trampoline works very well my son loves to jump off anything no fear even his grandmothers couch from the top, and it would scare me to death just knew he was going to hurt himself, a friend recommend the trampoline to me. You can get them at wal-mart, toy- r-us and there not that expensive I've seen them from $40-100. And there even easily put away just unscrew the handle and slide under a bed or put in closet . And as far as the talking back I cant help you there my son does that sometimes to, this might not be the right way to do it but when he does which is not very much I just don't acknowledge it I feel like if he knows it affect me he will continue, So i just over look it but then again he don't do it very offend. Hope this can help you out.

It all depends on the function the behavior is serving. For example, if he's saying mean things to you in order to get attention from you, you would want to ignore what he's saying and then as soon as he starts acting appropriately, you reinforce that behavior by engaging him or playing with him. In terms of jumping off the sofa, this could be reinforced by attention from you or it could be something that is intrinsically reinforcing (he like how it feels to jump. One thing you might consider is using matched stimulation. Could he get the same feeling from rock climbing at the gym, for example? The other thing you might want to do, with the help of a knowledgeable behaviorist, is to implement a modified time-out procedure. Different problematic behaviors may require different interventions.