Well, I have a different opinion about this. My dh was NOT granted joint legal custody (even though he is regularly involved in the child's life.) As the judge put it, as long as CP & NCP can't get along, only CP will have legal custody. Of course, I don't agree with this at all, because this just gives the CP the ability to be uncooperative just so that she can retain sole legal custody.
So, I think that how you approach this will depend on the judge more than the law. If you are dealing with a judge that would prefer a joint custody presumption of any kind, then your evidence may be beneficial, but if you've got one of those judges that just doesn't want to mess with the issue, you might get screwed. If you think that you are dealing with a judge who might do the latter, then your best bet may be to ask for sole legal custody. I know you want joint custody, but if you have a choice between no legal custody and sole legal custody, at least with sole legal custody, you can allow the other parent to participate in decision-making. If legal custody is taken from you, you will have no say in anything. Most importantly, your lawyer can probably tell you best what you should do.