That has to be one of the biggest loads of crap i've ever heard. M1's rarely jam. It's easy to jam your thumb in the action when trying to load the clip improperly, but the gun is very hard to jam, unless you shooting garbage ammunition, or overpowered ammunition (bending the operating rod). Also an issue may be if you never clean the gas cylinder, or never clean the gun after using surplus corrosive ammo.
I know several M1 nuts, including two armorers who used to build them day in and day out. Never heard of a design defect of any sort as you've described. Most target shooters modify their rifles to shoot single rounds (basically buying the single or three round match clips), usually because it is a match that allows single shots only, and loading a specially designed single round clip in the gun is easier than loading a single round into the gun using a standard garand clip.
A garand is a great choice for a rifle, and many a person will swear (and have sworn) their lives to it...but you must learn the rifle... If you hardly ever shoot it, and have the occasional issue loading it, it's not a good idea in a home defense situation. If you for some reason start having issues trying to load it, right when you need the gun the most....it's going to cause problems.
With that said, If you spent $1k on a garand...you can get yourself a pretty darn nice one. And you'll still be a couple hudred dollars in the green compared to an M1A/M14. Just be careful what you feed it.