I went ahead with a clean install of 16.10, and, coupled with the following firmware update (http://downloads.dell.com/FOLDER04078627M/1/XPS_9550_1.2.18.exe htt

I went ahead with a clean install of 16.10, and, coupled with the following firmware update (http://downloads.dell.com/FOLDER04078627M/1/XPS_9550_1.2.18.exe http://downloads.dell.com/FOLDER04078627M/1/XPS_9550_1.2.18....) seems to have resolved the Intel graphics flickering. Thanks a lot for that nudge in the right direction!