I think it depends whose funeral it is..I would'nt just take them off to anyones funeral it would have to a family member or friend.
Our kids have been to several funerals family members & a close friends husband..I think for us it was important to honour their memory with the presence of our kids, they loved them and wanted to be around them..In life no one was worried about a bit noise and certainly if it was to the point of affecting other people we would be prepared to go outisde etc..
For us it would feel wrong NOT to take the kids.