Well, if she was indeed a prophet, we must remember what the Scripture says about God's prophets:
"Believe in God, and thou shalt be established. Believe His prophets and thou shalt prosper."
I don't know a single person who's been hurt by reading EGW. The Health Message has proven to benefit countless people; the counsel on Christian lifestyle, marriage, rearing children, etc., are indispensable. Many Adventist preachers know that non-Adventist preachers are using EGW's writings because they hear them quoting from her writings, sometimes verbatim, but they can never admit where they are getting their info from, which is cool - as long as people are hearing and accepting truth, that's all that matters.