Long story short: I bought a Surly rear hub a few months ago to keep on standby for when I inevitably blow up the stock unit that came on my single speed GT 29er again but to my surprise it hasn't blown yet so I've now decided on a whole new wheelset with a matching front hub.
As for the original, I'm on the 4th one under warranty already so it was becoming obvious it wasn't up to the job. However, it turns out I'm not the only one blowing these hubs. They're a generic item rebadged under various names and were standard equipment on Single Speed GTs & Redlines amongst others and they appear to be susceptible to water. Water gets in and they very quickly get noisy and seize up or break. The last one I had replaced we overloaded with grease and it's still going strong but it is starting to make noises and skip occasionally now so it's not long for this world.
I decided on Surly hubs for a few reasons. Firstly, they're solid and over-engineered with adjustable bearings, and they're not expensive. Secondly, my standard hub is a cassette style with a lockring and the freehub is integrated into the hub and can't be upgraded. I had similar problems blowing freehubs in my old Giant Rincon which came with entry level Shimano components. However, they were able to upgrade me to a beefier freehub with that one and it gave me no more problems. With my stock GT hub that's not possible and after looking at a few other (dear as hell) cassette style hubs and remembering how difficult it was to find straight cut gears (no ramps or pickups for derailleurs) I decided a screw on freewheel like a BMX was a better proposition. Freewheels come in a variety of price levels and gear sizes so I can break them as much as I like knowing there'll always be a better one to try.
So how did I end up deciding on a whole wheelset instead of just swapping out the hub? Well, considering it's also time again to respoke the wheels anyway, I decided I may as well grab a matching front hub and throw in a pair of new rims as well, then I can keep the old wheels as spares. And with a bit of (perhaps bad) influence from http://fixedgeargallery.com/ I thought a bit of colour would be in order while I was at it so a brand new set of bright yellow Velocity Blunts are on order. They look like this -
LOL!
It could be a month or so away yet until the Velocity factory does another lot of yellow powder-coating because for some reason they only make yellow for the USA market and not here so mine have to be specially made up. :)