Coppertop, it sounds like your neighbours are related to my old neighbours.
We had exactly the same probs as you have described and the kids involoved also didn't come from happy homes and so at first i was reluctant to complain as i wasn't sure what trouble they would get in to, i mean yeah i was annoyed but didn't want to find out that they had been beaten cos of it.
Anyway the lad upstairs became more and more agressive, shouting and swearing at us whilst kids were with us etc and so i did complain. We also complianed about the very loud music and all night parties.
We had to keep a diary, logging each and every event. I would do this from now imo as it is so hard to remember what happened when etc, and also make sure you put exact details, ie if he told you to F off then put that, just putting that he swore is no good.
As to wether it will cause you more probs, it is hard to say, but if i had to say one way or aother i would say Yes it probably will.
Once we started the ball rolling (we wern't the only ones complianing either) then we got blamed for every complaint made against anybody. We had the downstairs neighbours accusing us if reporting here for everything and anything when we hadn;t and so then her and her kids started mouthing off when ever they saw us too.
The problem is, that basically these people do not care and so instead of finding out a complaint has been mader and thinking 'oh well we better try and behave', they think 'what the hell are they playing at complining about us' and turn the heat up.
We had meetings with the police on several occasions but tbh completely honest they were pretty useless. We were also told several times that they were going to be served with asbos and it never happened, there was always some excuse.
I would defo complain to the h/a, discuss situation with police and keep a detailed diary BUT I would also be very very wary of telling anyone even peple on the estate that you are friends with, because we found out that people so love to stir it.
I have obviously moved now but my old neighbour still hasn't been evicted despite the problems continuing. The h/a have witness statements off 5 people including myself and we all agreed to go to court over it but again now the h/a are dragging their feet becacuse for the mo she is being good.
If i can be of anymore help then just shout.