I think if you don't remove that border you will always be aware that the problem is there and never be happy with the finished quilt. Though I'm certainly no expert, it's hard to understand how a longarmer could deal with it to your satisfaction in the end.
I do want to add that I agree that the quilt top without the border is beautiful, but the pattern is complex enough that just a binding would be prettier on it, IMHO only, of course. The current border fabric doesn't seem to quite fit with the rest of the fabrics colorwise.