The shorter 1911s do require more frequent spring changes. A smaller spring is being asked to do about the same work as the longer GI springs so it won't last as long. 500 rounds is about the max they should go. Some will say 300. It's part of routine maintenace for short 1911s. It's only a reliability issue if you don't change them when you should. FYI - even a government model should be changed after 3,000 rounds. Possibly less if you shoot a lot of +P ammo.
If you want to go longer, consider an STI. Their RecoilMaster will go significantly longer due to a different design. My Shadow has 3,000 rounds on the original recoil assembly without problems. My Escort has over 1,000.
The Defender is also typically reliable. Mine has zero failures in well over 1,000 rounds, but I do keep up with spring changes.
The shorter 1911s do allow less margin for error on the part of the manufacturer and on the part of the user. I personally don't think Wilson et al don't make them because they are impossible to make reliable, I think they are happy with their market share and don't want the hassle of making one work and then dealing with customers who may not keep up with the additional maintenance requirements (either through ignorance or neglect).
Kimber has some issues these days aside from common 3" issues. They often have improper extractor tension (too little), out of spec feed ramps (too shallow top to bottom), and tight chambers (which are good for accuracy but make it more difficult to chamber a wide variety of ammunition). Their slide stop lobes are sometimes too big which allows them to contact the next round in the mag, which in turn causes false lock backs.