I purchased Jaikoz about 6 hours ago, and so far, I'm extremely satisfied...
After seeing the wishlist sticky, I am VERY excited about the last.fm genre tagging support!
I am a DJ, and I sort all my MP3's by genre, so this feature will save me about 2 to 3 hours a day!!!
Fixing genres from MB has been added in 2.5.0 (beta).
Please try it out and let me know what you think - this includes submitting tags to Musicbrainz There is an issue in Musicbrainz that means its a bit slow to submit tags to Musicbrainz at the moment, so best to do this overnight.