Some feedback. I went on a cheap and tired XT600E and it was great (mostly) but check out the following!
Good things to do;
Air filter socks
Pirelli MT21 tyres - excellent
Heavy duty inner tubes
See if Ohlins do a rear shock. Expensive I know but re-sellable.
Take clutch/brake spare cables tied to originals, fork seals.
Riky Cross produce some products including a headlamp guard - may include a rack, engine guards. Oil coolers are nice and work well but XTs just don't need them. Save the money for the trip.
Big mistake to fit a centrestand as I did - no ground clearance. Lean
the bike over if you want to take out a wheel!
Old fork seals were knackered after a week's good riding on piste.
Rear shock was knackered.
I kept the original engine protection bar but a plate would be better.
Check out other bike prep tips on this site. Try not to take too much stuff as this will spoil the pleasure. Leave your northern european mentality behind - travel light & if things go too bad put the bike on a truck to the nearest capital and DHL out the spares. Take a few days break from the bike while the parts arrive!
I arrived in Dakar after a hard journey fully loaded, very proud, when a Finn on a standard XT with just knobblies and a small back pack arrived after completing the journey. Food for thought.
All the best, David