Regarding the hagons I have seen shattered springs (Siberia) and broken body (Morocco) at the UK 2007 HU meeting 4 travelers had stories of broken Hagon Shocks. One traveler had a replacement fail on the same trip. As Bob said their back up is by all accounts good.

Now what to choose is the BIG question. Do a search on the HUBB and you will find plenty of info. Talk to suppliers and tell them what you are looking for.
Ask the same question of riders who have done the trip you are planning.

A lot of shock manufactures are very sports orientated, but durability is high on your list. The Japanese OEM shocks rarely fail but they are not the best in performance. If your shock is original the seals have most likely failed because of age. If was riding solo I would put an OEM shock on the list. OEM shocks are not always repairable

All the WP shocks (4) and forks (1) I have used have leaked oil between 8,000 to 20,000 miles.

A leaking shock is not normally a show stopper and you could carry a repair kit with you or find someone to rebuild it. I would choose a good brand, low tech, rebuildable emulsion RSU.

A couple of manufacturers to have a look at.

Technoflex suspension technology

Wilbers Products GmbH - Die Fahrwerksmanufaktur!

Info
http://www.horizonsunlimited.com/hub...rica-twin-8770
check out your bike on here
Adventure Motorcycling - Trip Reports

let us know what you decide.

Steve