KitchenAid Mixers, which one to pick?
I would recommend against gatting the models below 325 watt. The 325W models is easily strong enough for breads, cakes, and cookies. Although it does sound a bit tortured on heavier dough and doesn't like mixing tough stuff for extended lengths and gets warm.

The higher power models tend to have a different release mechanism where the bowl lifts into position and the mixing head doesn't tilt. This is generally handy (less dripping, and no wobbling of the mixing head). If you plan on using it multiple times a day, the pro models with higher wattage are the way to go.

I personally find the metal dough hook just fine, I believe the other one you refer to has a spatuala attached to scrape the dough off the sides during mixing.  Sometimes useful, but not the end of the world without it.