I'm after a light weight wheel set that will be tough enough to ride the occasional downhill track without falling apart.
Not a fan of carbon, as I've seen a few cracked ones about.
Is this achievable with an alloy rim and what should I be looking at in terms of build kit?
Yes.
I have some e13 TRS+ rims built onto some DT 240's with Supercomps & brass nipples. Near enough bang on 1600gm.
They have survived some uplift days, DH races, enduro races, a week in the alps & 2 weeks in Whistler. Still going strong.
Some dt Swiss m445 rims on the same hubs and spokes as hobnobs would also come in at 1600g
I haven't heard much about e13 wheels other than the hubs are a bit poor. How are the rims compared to say an arch ex?
It depends on heavy you are and how heavy you ride.
For me a set of (26") Crest shod Hope's works pretty much every where I ride, and that includes some of the DH trails at Inners.
The E13 hubs are laughably crap, but the TRS rims are pretty good.
If you arn't a rim killer, you could probably get away with a DT XM401 as well.
American wide lightening, seem very strong here for there 1550g weight! Don't know about full downhill though!