I have an LEM dehydrator and absolutely love it. It is a cookie live saver as it allows you to complete cookies much more quickly by almost eliminating having to wait between steps if you are working on a set of cookies. For example, by the time you have flooded 12 cookies, the first cookie you flooded will be just about ready for the second layer of icing details.
I don't notice a change in my cookie's texture or taste from the dehydrator. All a dehydrator does is heat up the air in the unit (some also have fans that blow the air, which is best for cookies). At 95-105 degrees, you are not subjecting the cookie to extreme temperatures and you don't have to leave the cookie in for long. Mine usually spend 2-3 hours total in the dehydrator.
Georganne of Lilaloa wrote a post about using a dehydrator and the affects on cookies: http://www.lilaloa.com/2012/06...hat-you-need-to.html
If you are interested in getting a dehydrator, I cannot recommend LEM products enough. They have flat trays, adjustable temperature settings, and a fan. These three features are all important for dehydrating cookies and not found on cheaper models.
Dehydrators also leave royal icing shiny when dry, so the cookies are more visually appealing than cookies that are air dried. Most importantly to me, dehydrators virtually eliminate craters in icing.