I bought my GMC Envoy new in March of 2003. I have driven it 113,000 miles with a few small problems but nothing major. The truck however is on its third ignition switch.
Normally I drive to work and errands, and do not think I am "excessively" starting the SUV to wear out the part. My dealer says that particular ignition switch is widely used in the GM product line up, and blames GM for "under designing" the part. Has this part failure been a problem for GM for many years like my dealer claims?
It looks like that design ignition switch has been used in various GM built pickups and SUVs beginning in 1998. In general, I recommend OEM (Original Equipment Manufacturer) parts as opposed to aftermarket brands. OEM parts are typically of higher quality, designed with narrower tolerances, and there is less chance of getting the wrong part or one that "almost" fits. However, there are always exceptions to the rule.
If the service personnel at the GMC dealership you're working with have noted replacement of this particular ignition switch as being a common event, then that particular ignition switch may very well be a weak link. That being the case -- and if it fails again -- replace it with an aftermarket ignition switch from a local parts distributor. One part may not have the defective element which is failing in the other.
Keep in mind, there is a Technical Service Bulletin (TSB) pertaining to the ignition switch in a 2003 Envoy and other vehicles. GM TSB number: 04-06-03-002 does not deal with a defective switch, but the tendency of the switch to be installed incorrectly.
The ignition switch is mounted to the lock cylinder assembly inside the steering column. During installation of a new switch, a gear protruding from the switch must be "indexed" (lined up) properly with the lock cylinder assembly. If it's off a tooth in one direction there may be a power drain on the battery while the ignition is in the OFF position. Off a tooth in the other direction may cause an intermittent no-start condition.