Hi Tony!
Congratulations on the imminent purchase of your new Nomad Mk2! This is a wonderful time, full of excitement and intrigue as you decide what is best for your needs -- fun stuff!
I'm not sure if this will help as a data point, but here's my story:
I chose an all-black Nomad to aid stealthy camping. I'd wanted all-back Ortlieb bags all-'round for stealthiness while camped...and ended up with black-and-red 'cos they became available at such a great sale price it trumped all color choice and I decided saving money was a real priority. It's hard to argue with 70% price reductions!
Having bought the bright bags, then what wrt stealth camping?
My tent is green and I've found I can place all my bags out of sight under the small vestibule if necessary, effectively hiding them from sight and so drawing no more attention than the all-black bike and green tent alone would do. Also, the tent effectively blocks views for its entire length so if I wish, all I need do is line-up the bags on the off-side if the tent is parallel to a nearby road and they are also hidden. The same pretty much holds true in many circumstances if I leave them on the bike -- which is also parked behind the tent propped up by a Click-Stand or laid flat as need be. For my stealth camps, I often get off the road just enough to place a screen of brush between me and the roadway, dirt road, etc., so the tent is my main source of camouflage. It is all leaf-green with the head end black, so depending on circumstance and how late it is on arrival, the lot can be placed to best advantage. I only ever stay the night before moving on, so continued stealthiness in a given location isn't as important as hiding reflectors from car lights at night -- those Ortliebs include some very bright 3M Scotchlite patches!
My point is, despite ending up with some very bright bags, they haven't really compromised my stealthiness when camping...if I plan a bit in advance when setting up my camp.
As for deliberate visibility when riding in traffic, remember Ortlieb bags are generally black front and rear when mounted on the bike with the colored panels most visible to crosswise traffic. I think the bright rack pack will help with traffic visibility no matter the color of the panniers. For visibility in traffic, I prefer to wear high-viz neon jerseys and jackets, as they are more in closing drivers' line of sight and provide a lot of surface area. Of course, I take them off or exchange them for something more subtle when in camp (my cold-weather clothing is all-black; I've found it absorbs a bit more heat from a watery sun in the cold of dawn and is of course less visible).
Grey can be a very stealthy color, blending in nicely against foliage and such and perhaps looking not unlike granite boulders, depending on location. They can always be removed from the bike and placed behind the tent or inside and the bike laid down, the tent hiding the lot.
Hope this helps.
Best,
Dan.
