I have 2 CX bikes, plus a couple of 29er MTBs so pretty familiar with the pros/cons of each. Put simply, if I want to go the fastest from A to B cross-country, I ride a CX bike - it's only really technical downhills that holds you back. I passed a group of MTB riders grinding their way up the Quantocks - the look on their faces as I passed them uphill on singletrack. Rode the inaugural Dorset Gravel Dash last weekend - 7 out of 10 bikes in the top-10 were CX despite the hub-deep mud and water in places.