I had the same dilemma when buying my first Thorn in 2011-2012. I initially thought I needed a Nomad, but was persuaded by Thorn that a Raven would be better suited to my stated needs of touring with a full load for a month, mainly on-road, but with moderate use of tracks and paths, in Western Europe so no need to carry large stocks of water or food.
At that time, there were still a few Raven Tour frames available, so I chose one of these as being very slightly (according to Thorn) more heavy-duty than the current Raven.
Due to a change of employment, I haven't done any long tours since, but the Raven Tour has coped perfectly with carrying my own and most of my wife's luggage on shorter trips for mixed cycling/hiking holidays, including some moderate off-road use. My load was front and rear panniers, plus à 48 litre rucksack strapped to the rear rack. No camping equipment, but two pairs of walking boots, which are probably about the equivalent of a tent in bulk and weight.
My take on the Nomad vs Raven debate:
for heavy duty touring with moderate use of tracks and paths, a new Raven or a second-hand Raven Tour is probably the best choice if you don't intend visiting really remote areas where you have to carry large amounts of water or food.
for mainly off-road use I reckon the Nomad is a better choice as it is possible to fit even wider tyres. Nomad is also better if you need to carry large amounts of water or food (desert crossings or some third world countries), or significant extra equipment over and above a normal touring load.