So after the sector shaft break on my jeep, I've spent a lot of time researching steering boxes, hydraulic ram assist, spare sector shafts, etc. Here is what I've discovered thus far...
Best thing you can do to alleviate the stress on your sector shaft is have hydraulically assisted steering.
If you own a 2007-Mid 2009 JK or JKU, you have a steering box that was manufactured by Delphi. These boxes were made in a few different countries. An easy way to identify these boxes is they're typically not painted, unless you've got a remanufactured box which were sometimes painted black. Some boxes were also cast with Delphi in the side of them. There are spare sector shafts available for these boxes (~$150). There are also rebuild kits available for these boxes.
If you own a Mid-2009+ JK or JKU, you have a steering box manufactured by Nexsteer. This box was made in China and are painted black with no castings on the side of the box. These boxes vary slightly in design from the Delphi boxes. The sector shafts are not interchangeable (as we found out on the Rubicon a few weeks back) and there are no replacements available. So you would be stuck carrying a spare steering box as a trail spare (~$871 w/ dealer core charge). I've heard that you can find them online for a little less, but haven't verified that.
The consensus is, the boxes are interchangeable, but the parts are not.
What I plan to do is locate a Delphi box and have that sent in to PSC to be ported for hydro-assist. This will give me the option of carrying a spare sector shaft, instead of a complete box. So if anybody is looking for a couple of Nexsteer boxes, I know where you can find them.