Hey ArtVark.
I'll give it a go allthough you should not take my suggestions/ideas as the end-all be-all to your questions. Ask around (like you're doing) and get an idea of what might work for you the best.
I've just completed a trip from Denmark to Capetown (west coast) on my R and am actually writing this while in Capetown. So I've experienced a fair bit of the terrain you're about to venture into.
1. Catalyst free cans is widely regarded as a must. I believe it is due to the
theoretical possebility that your catalysts might otherwise clog up and stuff the exhaust system completely. When I say "theoretical" it is because I have not heard accounts of this actually happening. But better safe than sorry. I personally went for the Arrow dual cans. The "low" groundclearence has never been a problem for me, but as you say, it can never hurt. And I agree with that completely. The reason I did not go for the 2in1 is because I wanted to save myself the money and trouble of after fitting a powercommander. Took me 10-15 mintues to both remove the old cans, and fit the new ones. Easy peasy. But I wont discourage you from going with the 2in1 option. Just make sure you know what it entails. Both money and time wise.
2. The lambda probe is not a problem with regards to functioning on leaded fuel. I simply left mine as it was and just went for it. No doubt, it has stopped functioning by now, but the onboard ECU on the bike handles this situation by ensuring a rich enough mixture so as not to damage the engine. You may get a bit of "farting" when motor-breaking down inclinations, but it's nothing to worry about. Prior to leaving, I disconnected the lambda (not the actual lambda. Just the electric plug) and I'm not even sure my mileage went down even one kilometer. But again, if you plan to go for the 2in1 solution, you needen't worry about this stuff.
3. Centerstand is an absolute must if you are traveling alone. If you travel with others, get help to lift the bike up and rest the bashplate on one of your panniers.Trust me...it works
. But this solution is quite impossible if you are alone. And even when traveling with others, you often find yourself alone. Go with the centerstand. Make very sure that the centerstand you have in mind, does not conflict with the bashplate.
4. From the picture in your other post, the handlebars look good and protected. Be sure that they are actuall crashbars and not just bush-bashers (flimsy donkey ear plastic things that you can bend with your fingers). I've dropped my bike numerous times, and never broken either clutch or brake handle due to having my handle crashbars. A rider I traveled with for quite a while (on an old Honda XL 600) broke both his clutch and his brake lever. The clutch lever broke when we were taking a rest and he rested himself against the bike and it fell over. Nothing dramatic, but it broke the lever. Luckily he had a spare. But he didn't have a spare brake lever, so when that broke, he had to complete the rest of the way without it (there was a stump left so he could actually brake. But not too well).
5. Bashplate. A must must must! Especially if you do not get the 2in1 and go with the standard underfitted exhaust like I did. Try and get a realy wide one so that it also protects the waterpump on your right hand side.
6. Custom grips. In my oppinion, that discussion is academic at best.
7. Shocks. I weigh around 100 kg and lets say 110kg fully geared. You should have no problems at all. First order of business though, is to tighten up your spring to the fullest (use the tool that comes with your R, under the seat). So much easier to park the bike on uneaven surfaces (less wobbling) and also makes your centershock travel/work less, when going on bumpy sections.
8. I'd like to comment on your tank, but not sure what you have. I have the OTR carbon fibre one. And apart from a few problems I had in Mauritania I am happy with it. Do you have a pic of it?
9. I used the regular paper airfilter. You
can actually clean this sufficiently by just slapping them onto the palm of your hand. But if you can get your hands on the "spungy" ones (dunno what they are called), I'd go for those. They might be easier to clean completely. I travelled through the Sahara and most of Mali (including Timbuktu). Allthough I did change the filter prior to Timbuktu, the original one could easily have gone for the rest of the trip with a few slaps on the hand. Realy.
Did I miss anything?
I could propably give you a few good ideas as to the rest of your equipment (bike stuff as well as none bike stuff). Feel free to ask away. For the next couple of days I'll be "grounded" in Capetown and should be able to get back to you fairly quickly.
Best regards
Torsten
PS: Welcome to XT660.com