Yes I used the airside transfer. I feel this just saves you the immigration procedure, as then there was the security check.

From T4 back they did check the boarding pass prior to getting on the bus - twice actually, the guy who earlier notes our visit in a log, and then 50m further at entrance to the bus a lady more thoroughly checked it and made a photo of it?!? Anyways no problem came up.
And boarding passes didn’t need to be stamped. They actually were on low quality paper, issued by Emirates with not even any logo on them. Probably they have revised their rules since these blogger’s experience.