I'm a Kitchenaid fan too, and have actually been looking at their line higher than the 600's.
They have a 7 qt Proline Series with a 1.3 HP Motor in the KSM7500 sku's. To convert for comparisons sake, the 600 has a 575 watt motor, while the 1.3 hp converts to ~956 wats.
Like the 600 series it has full steel gears as well, and same realtive form factor, just a heavier duty version with a much stronger motor.
They even have a commercial 7 qt in the KSM7900 that has the same 1.3 HP motor, but is even more robust.
One of these might be worth considering as an all-in-one.