I added a GTO 1100 with CP4 to my existing GTO 900 CP3. One of the reasons I did was because of the Wireless. Sadly the wireless on the CP4 is problematic. I and others have issues of it dropping connections and than having a hard time reconnecting. I was one of the early owners of the CP4 and although there have been a few firmware updates on both the CP4 and hand controller, nothing has corrected the issue. I run Sky Safari Pro latest versions.  I finally had to go with a SKYFi latest unit which does work flawlessly with Sky Safari Pro. I run with a couple of Samsung Android devices....tablet and cell phone. I know AP has been trying to figure out what the issue is but not having any luck. Those runnng Apple devices may have different experiences. 
In short if you are happy with the CP3, and want wireless the SkyFi unit does work great and you won't need to upgrade to the CP4....especially for visual.

I can't figure out why SkyFi works so well and AP doesn't. Perhaps it is the wifi module in the control box itself.