You couldn't be any further from the truth. The pro2 changes the geometries so much that it has zero the same as the slash.
The protrac suspension kit has wider arms and wider turnbuckles and shock mounts in different locations along with shock towers that place the shocks in different spots. The transmission gearing is different from the slash and is closer to that of Team Associated. The steering kit changes the Ackerman and eliminates the bump steer that the slash has. The center of gravity is a lot different from the slash as well.

I built a pro2 out of the upgrade parts before the pro2 kit was released. I raced it compared to my slash and it was a HUGE difference. It did not feel like the same truck at all. The truck has a lot more aggressive steering entering a corner as compared to a slash. It puts the power to the track more efficiently and more predictably than the slash. It is far more durable the SC10.2 and if they were to update it and install the pro spec shocks instead of the power strokes than it would be awesome.

The pro2 is a lot of money up front as compared to the others in the class, but look closely and you'll see it's the same and in one package.
The pro2 can be found for about $360 on average. The sc10.2 and 22SCT are $260-$290. Then you have to buy a hi-flo body (which the pro2 comes with) as new wheels and tires to match the truck (which the pro2 comes with tires that work at nearly every track) so by the time you buy the truck, wheels/tires, and body; you're now around $340-$370. Right at the price the pro2 sells for.

As for the made in USA topic, I would love to see more companies that are made in the USA in our hobby, but unfortunately it's not cost effective for most of them since it's so cheap to do it in Asia.