It's usually not a big job to install a wired unit, except for something like a Campy ErgoBrain which I never want to install again! But some people want the cleaner look of a wireless, and that's the main reason I bought the Micro. It's an awesome unit, and I must confess I got a great deal on it from a friend who wanted the HRM version.
If I had any problems to report about it at all, believe me I would.