The Trumpter M1 series (repackaged by HobbyCraft, as I understand) is not a copy of Tamiya's M1A1. The Chinese offering is different than the Japanese kit in many ways; such as parts breakdown (more parts) and general detail (more accurate such as the anti-slip surfacing, but less crisply molded).
The only similarity between the two kits are the poses of the figures.
IMHO, the Trumpeter captures the overall accuracy of an M1A1 better than the Tamiya version, although the former made a serious shaping error in the turret's front - although that can be rectified by referring to the Tweaks List provided in the link above. Im my experience, the most difficicult aspect of building the model is the extensive and tedious cleanup required.
Hope this helps.
BT6