Hi Tom - if you've not bought one yet, I'd echo what Scottnet suggests and certainly go for steel rear teeth... You might want to consider a Supersprox rear (alloy centre and steel teeth) if you can get one for the stock Tenere hub (I think you can, it's the same PCD as a Yamaha Diversion as I recall) - I fitted one on the Tenere before the rally, rode all the way from Paris to Dakar with it (and with a dry chain), through all that sand and sh!t, and it still looks almost new! Worth the �45+ they now cost unfortunately...
I'd also recommend a DID XM chain - again, top quality and long life...
xxx