I tried out my 2018 RE Hex at the Weekend setup with normal fixed hook and gotta say that I love it, but I have loved all the previous versions. The updates this year are to the velcro belt, the foam on the inside, much improved webbing and of course the new closure system. Personally I've never had any problems with either my 2016 or 2017 - the 16' was probably not as polished as it could be coming to market, which was addressed last year IMO. However, this year is an evolution to the design and with the new setup you can cinch it in tight very easily and it just feels even more secure.
That said I've never had a problem with it moving or the bar riding up and I think this is because I have found the perfect fit for me and this is the key thing with the RE harnesses. With other brands (non hardshell) there was enough slack in the design i.e. adjustment, size of harness plate, pliability etc that they could fit a huge range of shapes and sizes. With the RE you need to get the sizing and fit right so that it 'sucks' into your lumbar area and make sure the bar length is correct for your hips to prevent any compression or upwards movement. If in the UK you can speak directly to the guys at www.rideengine.uk
and let them know your size and what you have used before and they should be able to get you exactly what you need.
I've also tried some other brands hard shell attempts and a few friends have also switched from these to the RE as the adage the original and the best has never been truer. If you want the maximum amount of support and freedom of body movement with the most minimal fit then the RE is still harness to go for and with the 2018 improvements the best just got better. Perfect.