The first thought that comes to mind is to opt out of them providing the drywall.

I would think the price would have to be phenomonally less to consider a prefab SIP home from China.

Possible problems include:

If the materials are wrong, damaged, inferior etc. how are you going to get it fixed.  Can you afford to wait 3 months whenever this happens (If they choose to fix the problem)?

Will you be able to permit the home in your local municipality?  You could not where I live.

I assume you will have to pay for most or all of the cost prior to shipping.  What if that is the last time you hear from the company?  How do you have any teeth to go after a foreign company?  This can be hard enough when dealing locally.  I've worked in China as well as being involved in import/export with China.  You almost have to experience it to fathom how mind numbing the lack of responsiveness or concern can be.  I would be very careful about depending on this to build a house.

I would advise staying local.  Even with local suppliers you better do your homework if you don't want to get burned.