@Oddjob speaketh great wisdom on the alloy nipples. If you buy a standard wheel with alloy nipples, you are letting yourself in for a world of regular irritation as big guys break spokes at a way higher rate than lighter guys (I have to fix a couple spokes a year even on my road bike, and the next one might trash the wheel as the nipples have rounded). Realistically, your wheels and drivetrain are where your biggest reliability traps will be found. Fo5r example, in addition to the spokes I have busted hubs which dumped me on my face, chains, and even broken cogs off the carrier.