Some simple math. Typically 55-60% of your weight is onthe rear wheel. With the dish in the rear wheel (the hub is offset to the left to make room for the cassette cogs), the right side spokes are near vertical and have considerably higher tension to oppose the left side spokes, roughly a factor of 2. So 1) front wheels have equal spoke tensions and all the spokes can be laced tit he best tension. THey also see less abuse because the see less weight on them.

Now, rear wheels have a huge imbalance between right and left. The result? Right side spokes have to be near too tight just to keep the left spokes from being too loose. If the spokes are equal diameter left and right, both have to be pushing their respective limits. Too tight - rims crack, hub flanges crack, any shortcomings in the wheel build and spoke heads are likely to pop off. Too loose and the spokes go slack as they pass the bottom of the wheel rotation and your weight is pulling the hub down. This leads to fatigue failure in the same places, spoke heads and at the start of the threads.

You say you are heavy. I suggest having a custom wheel built by a reputable wheelbuilder with heavy spokes on thet right and spokes a full gauge thinner on the left - and have the spokes on both sides "butted", ie thinner n the long middle section than at the ends so you have both more material where they break and more stretch in the middle which allows the spokes to stay "tight" at the bottom of the wheel rotation and not go into fatigue mode very wheel revolution. This wheel will be expensive. But done right, it will give you good service.

Oh, and think about seeing if you can "ride light". All l of us who build wheels know that weight isn't the entire issue. Some riders at a given weight are easy on wheels, other killers on the same wheels, riding the same roads. Whether you hit a road issue (pothole, rock, crack, etc.) and how you manage your weight on the bike when you do hit (we all do, even the most aware of us) matters a whole lot.

Spoked wheels - one of the key inventions that allowed the bikes we ride today to happen. We owe a lot to that, pneumatic tires and the chain. Without these three things, we would still be riding 80 pound high wheelers. (But the inventors of the spoked wheel never dreamed we would, 100 years later, be putting that huge amount of dish in the rear wheel. In fact, they would simply say that wheels built that way were to be considered "bad wheels". Now we have to jump through hoops to make these bad wheels work. Aside: I do half my riding on fix gears which use rear wheels with virtually no dish. I use the same spokes as I use on front wheels and get the same life out of those wheels. They go forever; until I wear out the rim from brake wear.or I've damaged the rim on bumps - bunny hopping not being possible riding fix gears.

Ben