I always used KMC 10 speed chains in the past. I decided to stick with Shimano 11 speed chains with my newer bike. I had a real hard time installing the Quick Link first time around. I always lined up the KMC Missing links and ran in though the big ring and it would snap into place. No such luck with the Shimano Quick Link. I must have tried about a dozen times. It would drop off onto my garage floor. Finally I put it in the small chain ring, small (11 tooth) cog in back and it went into place after I placed pressure on the pedals (I acually rode a few feet) and I heard it click into place. I never had any luck installing a connecting link with tool. Near impossible to get one off without one. Note -these are only good for one application. If you remove your chain, you need to install a new Quick Link (per Shimano). However-no need to remove your chain for cleaning.
I have used SRAM, KMC, and Wippermann Connex connector links in the past with no real installation issues. Nevertheless I recently purchased a Park Tool MLP-1.2 Master Link Pliers which made installation and removal of KMC links an order of magnitude easier. The recent purchase of a Dura-Ace 11-speed chain came with this new Shimano Quick Link instead of the usual pin. I dutifully tried to use the pliers (which work in both directions for installation and removal) to seat the link after partially engaging it. The link would not seat no matter how much pressure I applied to snap it into place. A call to my LBS suggested standing on the pedals and applying pressure. Before trying that, I took needle nose pliers and gently squeezed the outside of the plates to push them inward before trying the MLP-1.2 again. THAT WORKED! The link snapped into place and has worked flawlessly while riding. Ease of removal is TBD.