I've been a vocal fan of SRAM's DualDrive hubs. This is what i wrote in another thread a few weeks back about it after using it for 25 months.

'25 months on...
Twenty five months on, and I've had absolutely no problems or issues with the SRAM DualDrive hub. The bike was bought second hand so the hub's been going for longer than that. No mis-shifts, no noises, no discernible resistance, no clickbox falling off, no maintainace woes, no adjustment, no nothing. The thing just works. Period/full stop.'

Those who say that a derailleur system is just as good or better obviously forgot that a long cage derailleur on a 406 wheel is risky. What derailleur system is going to give me on a 406 wheel the 18.6-113 gear-inch range that the SDD hub gives me using a RD that hangs well above the ground?

Then there are those who the clickbox is finicky, fragile and difficult to source. Simply not true. In 25 months of use, often in the rocky country roads of Bali, the thing has never come off, and it remains intact. It can be easily and quickly sourced from Amazon.