Board Thread:General Discussion/@comment-72.89.162.24-20130812014139/@comment-183.90.41.21-20130812172113

It's best for you to bring this question to the vocaloidotaku forums rather than here, as the people there are more experienced with the use of multiple English vocaloids. This might help you:

http://www.vocaloidotaku.net/index.php?/topic/39398-using-gumis-english/page__hl__gumi

Think the consensus is that Gumi English sounds fine but working with her can be a bigger pain then you expect, as basically she could have been a great English vocaloid but Internet Co did a rush job on her.