I found the Tubus racks were pricy enough, that I did not need the titanium ones.  Or stainless.  As I noted before, I use black fingernail polish to touch up any spots where the paint is worn through.  With the brush built into the cap, takes less than a minute from start to finish.

In my previous post, the third photo had the rear part of my Lynskey with the Racktime rack.  That bike has a titanium frame.

For riding around near home I use a Nitto that I picked up used at a swap meet instead of the Racktime rack.  I was surprised how heavy the Nitto was, but it looks so nice that I weigh down my titanium bike with the Nitto rack for riding around near home.  See attached photos.  The pannier in one of the photos is my gym bag, not used for touring.

Point being, on Nitto racks, check the weight before you order.  That said, they are beautiful and top quality.  But for a touring bike, the bike is supposed to have some nicks, scratches, and bruises.

Thanks, all!

That's very helpful, although I'm still undecided.  I'm still considering the Thorn Expedition, but it seems that the lower pannier rails of some other racks would be worth having.

I did briefly consider titanium (I have a couple of titanium Bagman racks which are nice) but I'm not sure how much I'll use this bike, so I'd find it hard to justify splashing out on a really expensive rack.

I also spotted that the Rivendell\Nitto rack had the lower mount in an unusual position, so fitting it could be difficult!

That looks like a lot of fun, Ron. Thanks for sharing.
What chain ring & sprocket combination did you use? I was taking a closer look and noticed your chain looks quite loose.
TIA
Ian

I really like the lower rails on the racks I use for touring to mount the panniers lower for a lower center of gravity. 

On my Nomad Mk II or my Sherpa, I use the Tubus Logo EVO.  Solid steel rack, very stiff.  But, if you do not have panniers mounted, this rack top platform is quite narrow.  I only use this rack for touring, not for riding around near home.  For riding without panniers, I want a wider platform, use other racks for that.

And on my Lynskey Backroad I use the Racktime Addit which I believe is now discontinued, this rack is aluminum but still quite solid and stiff.

I use black fingernail polish to touch up wear spots, but for touring I put some plastic hose on the racks to prevent chaffing.

First attached photo, the Logo on my Sherpa.  No hose is shown on this rack, this was on a tour in 2012 before I started using the hose.

Second photo, I have one pannier on the Nomad with the Logo, you can see how the lower rail lowers the pannier nicely.  The plastic hose is quite apparant.

Third photo, the Racktime on my Lynskey. 

FOurth photo, I do not have a photo of the Racktime with only one pannier like the photo of my Logo, this is a photo from behind the bike.

My Logo is marked as rated for 40kg, the Racktime at 30kg. 

It is my understanding that they now have much lower ratings, as apparently the companies did not want their racks used for child carriers, and to do that they lowered the weight ratings to the point that they are not allowed for carrying child seats.

I need a rear rack for an old Overbury's mountain bike with 26" wheels.  I have a pair of Arkel T42 panniers.  I'd be using them for overnight camping trips - I imagine the total load, including panniers, would weigh around 25lbs (11kg).

I had a Thorn Expedition on an old bike, and that was fine other than the finish quickly became a bit tatty with rust and scrapes etc.  I never had any problems with it, and I remember it felt sturdy.   However, I'm wondering if there are better options considering I won't be loading it up to capacity.  Some rear racks have a pair of pannier rails which are lower than the top rails, which could make it easier to load\unload panniers when a drybag is strapped to the top of the rack.  Also, some racks have side frames which cover more of the rear wheel - so perhaps there's a risk of panniers flexing into the spokes with the Thorn rack.

Other racks I'm considering are the Old Man Mountain Divide rack, and the Rivendell\Nitto 'Big Back Rack'.  However, I think I may struggle to find one of these in the UK as the one place which sells them has sold out.  I'm looking to get the rack before the Christmas holidays!

I may still go for another Thorn rack, but I'm just wondering if there are better options nowadays.