The only problem I have had with panels is that some of them have been printed off grain. Drives me nuts! I have to decide if it is more important to have a squared up quilt or even borders. I usually compromise and trim a little plus fudge the borders a little. I haven't had problems with quality panels from companies like Moda, but I have had with some adorable baby panels from quilt shops. Sigh. I still use them because they are so cute, but be aware.
Pam