You are correct! Similar lengths but the tang on the micarta is full height so its extra weight gives a balance that feels great in hand.
The thermorun has to 'wrap' around the tang, so the tang cannot be as 'tall' - resulting in a handle that feels of similar dimension to the micarta model but IMO shifts the balance slightly forward. This also means that your bare hand doesn't touch any metal while being used in cooler climates (although the tang is still exposed for 2-3mm at the end for hammering). Some people don't like the feel of the plastic fantastic model, but I'm very happy with it. Great blade.
Hope that helps