Sturmey S3X concerns
I have no doubt Aaron has much more IGH experience than I, but I would beg to differ on the safety or reliability of the S3X.
I have been using two S3X,s for about 3 years, so both are fairly early, with two different set ups and ratios.
One for a go fast bike ( a relative term for me!) and a go anywhere bike.
While three years is not very long..... It's all I got!
While I would agree that an improperly set up hub can be (is) quite dangerous, a properly set hub, IMHO is not nearly so.
I learned this the hard way when I hadn't set up the hub cones up quite right.
On a tune up (maiden voyage) ride, it slid into a very wide neutral position. Then suddenly re-engaged.
After a very nice visit with an emergency room physician, I found some set up notes posted on line...
I do always ride with two brakes, however four brakes would not has helped.
This was me, the hub and the tarmac....
But after reading and proper adjustments they both have been quite stable.
The shifter is as precise as my AW hub and trigger seem to be.
The caveat being you must listen for/feel the locking click of the shifter as the hub engages quickly and may seem to be in gear correctly and isn't.
The go anywhere bike sees the roughest treatment but neither hub has failed me (again!).
I know about 6 people who bought s3xs and none of them are still riding them due to repeated mechanical failures and the slug like response time from sturmey on the warranty.