Extra sideways projection is on the order of 1/2 inch or less. This extra may be more prone to catching on things, but not much. It does position the counter better for direct reading, moving the readout a tad farther out from the fork.
With regard to easy reading, I have been using my chain-driven counter for 300 miles now, and I find that it is significantly easier to read while riding. Whatever counter finally evolves, I will never go back to anything that reads sideways. The improvement in reading is enormous. Must be seen to be appreciated.