I've had the chance to shoot a handful of Deadline's, some that were basically brand new and one that had ~3000 rounds through it. Both shot amazing, but there was definitely a smoother bolt throw on the broken in one (as to be expected). The bolt lift is night-and-day when compared to the old U300, but I believe they're using dual cocking cams now too (don't quote me on that), which aids with the heavier bolt lift that is usually found on 3 lugs.
Comparing the Deadline to the Barnard is a little weird, as they are generally used for different purposes (UP for hunting/precision, Barnard for f-class and ELR). Either way, I don't think you can make a wrong choice between the two, but depending on what the end goal of the build is, remember that the Deadline is pretty much a drop in fit for R700 chassis/stocks, whilst the Barnard isn't.