Here's a photo of traction alopecia that is the result of using clips to attach. Notice the round bald spot on this guy's hairline. That's where he attached with clips and the hair came out in that spot. Another big downside to using clips is that clips are detectable to touch. There's terrific glues and tapes that will give you a solid attachment. And if you looking to achieve an undetectable look--aren't we all?---then either glue or tape is the way to go. Many customers use a combination of glue and tape. The tape is used at the perimeter of the unit and glue is used for touchup.
Regards,
John
http://toplace.com/