Wogster

There are really 3 classes of road bike, they look similar but are quite different in use, first is the road racing bike, the idea is that the lighter the bike, the faster the bike, however they forget that the critical part is the engine, Frames are often made of exotic materials, and prices run from reasonable to exotic, geometry is exotic, and as for comfort, well, that takes a back seat to speed, after all the faster you go, the shorter the trip. Often these bikes are designed so that only the narrowest tires can be used, Bars tend to be much lower then the saddle.

Second class is the road touring bike, built to act like a mechanical pack mule, they have room for racks, fenders, several water bottles, most are made of Chromoly steel, relaxed geometry, designed for comfort, so you can spend many hours in the saddle. Designed for heavy loads, they have Clyde friendly wheels, and can accommodate wider tires. You want the bars higher on these bikes, even with or slightly above the saddle,

Third class is the cyclocross bike, intended for cyclocross racing, where weather and surface conditions are less then ideal, can be used for road riding with smooth tires, and off road with knobby tires, not as off road intended as a true All Terrain Bicycle (ATB) or Mountain Trail Bicycle (MTB) with suspension, they are built tough, and can accommodate Clyde sized tires. You may need to change the wheels though, as some have lower spoke count wheels. Again the bars tend to be higher.

Dropped style does have a big advantage, and that is multiple hand positions, although there are alternate bar designs like bull horns and moustache bars that will give the hand positions without the drop. The problem with straight bars is you only have one hand position, and it's not a natural position, relax your hands, at your sides now bend your elbow so your hand is pointing straight out, where is your thumb pointing, toward the sky or toward your middle? If your like most people your thumb is pointing straight up, this is the natural position for your hand, when you turn your wrist for a long period of time, like when typing, or when holding a straight bar, then your more likely to have cramping and numbness issues, then when it's in a more natural position. This is why on the hoods is such a common position on drop bars, the wrist is in it's resting position. The other advantage of drop bars, is that you have the option of the tuck position, where you go into the drops, and try for the smallest wind sail, going down a steep hill in this position, is how you set speed records.

Now as for holding 280lbs, most frames are engineered for much higher then this, if not, then the frame and bicycle should have warning stickers all over it with a weight limit, although such stickers may have been removed by a former owner if buying a used bicycle. The issue is wheels, the critical thing with wheels is spoke tension, as rider weight increases and/or spoke count decreases spoke tension becomes more critical. A 160lb rider with a 36 spoke wheel, as long as the spokes are connected at both ends it's likely to be okay, a 300lb rider with a 16 spoke wheel, and it's got to be within a very narrow range. This is why you don't often see low spoke count wheels on touring bikes.