I use a relatively low cost RockShox XC28 on my Nomad Mk II, size 590M.
I specifically mention the size because you want to make sure you get enough steerer tube. Since I use the Thorn Accessory bar as a handlbar bag mount, that meant that I needed enough steerer tube for a stem and the accessory bar above the headset. I have not cut any of my steerer tube off, and I would have liked it about 20mm longer than it is.
I bought a spare headset lower bearing race and star nut for the fork. With the spare headset race, I do not have to remove the race from my other fork to switch back and forth from one fork to the other. Used forks on internet auction sites often have the steerer tube cut down, watch closely for that if you buy used. I saw many forks that I would have liked to own but the stererer tube would have been too short.
The XC28 is a low budget coil spring fork, but I find it to be perfectly adequate when I want to use my Nomad as a mountain bike. But some have had a preference for a fork with 32 mm stanchions instead of the 28 mm that my fork has. The higher end forks are very hard to find that can take rim brakes.
NZPeterG on this forum also used a RockShox fork but his was a higher end one than mine.
I use the same brakes on both forks. I have only switched the bike over to suspension fork twice, so I have not found a great need to get another set of brakes. I have CSS rims, thus if I had a an extra set of brakes for the other fork, I would have needed to buy a second set of brake pads. If I did not use CSS rims, then I might have considered an extra brake because with normal brake pads, another brake would not have cost too much.
I use zip ties to strap my dynohub wires to the fork leg. I use the SP hub, that uses the same connector as the Shimano dynohubs. So I bought a spare connector so that I have wires zip tied to both forks that are ready to connect to the hub. I am not sure what connectors you would use with your hub.
I have not toured with a load with the suspension fork, I only use that fork when I want to pretend that my Nomad is a mountain bike. Thus I have not looked very hard at rack options. The Tubus Swing has been out of production for many years, I think that was the only rack that allowed you to put panniers on so that the panniers were sprung weight instead of unsprung weight. Minoura makes a rack that might fit on the RockShox, I do not recall the model, but that mounts the panniers so that they are unsprung weight. I looked at the Minoura rack as an option for my rigid fork, but I decided the rack was too heavy for my tastes.
I hope this helps.
ADDITIONAL COMMENT MADE A DAY LATER:
I above referred to my XC28 as a low cost fork, but it is not as cheap as some of the ones that lack metal coil springs. I was shopping for a higher quality fork when I saw a new XC28 on Ebay for a low price. I put in a low bid and nobody else bid, so I got it at a fraction of the new price. I originally was looking for one with 32mm stanchions, but I have found the XC28 to be perfectly adequate.
