I just had Mike and his crew write 10 articles for a my surfboard site and they did a great job for the money. I have no problems digging into these articles after they have been written and tweaking them so they sound as though they were written from an authority in the niche.
If you are building a true authority site, and need articles that would gel nicely with content, say, straight out of your favorite magazine, then expect to do some extra work once you have received your articles, which I do not mind doing. Mike did all the a hard work. Again, if you need super high quality, authority level articles, then Mikes service is a good start. Once he's written the article then you (who should be the true authority in your niche) need to work through the article and get it up to your readers standard.
Hope this Helps...