Which nRF development kit is suitable for BLE meshing.

[Arya]

Whether nRF51822 replaced by nRF51 DK and nRF51 Dongle

How nRF51 DK and nRF51 Dongle differ from nRF51822.

[Hung Bui]

Both nRF51422 (which is on the nRF51 DK and dongle) and NRF51822 should work with our Mesh SDK. However, as endnode suggested, nRF52 is a better platform to start your new project. Note that our nRF5 SDK now no longer supports nRF51.