Should I have any reservations about using the clone boards from China intead of the genuine Pro Mini ?
1- QC may not be as good so you could more easily get a bad board.
2- There will be NO tech support so if you have a problem you are on your own. If you buy from SparkFun you can get tech support and a replacement if it is bad.
3- A genuine Arduino supports the Arduino foundation which did the development. Does this matter to you?
Agree with waltr. Most clones will have missing parts and/or cheap parts to make the board cheaper. This results in a significant increase in faulty boards or boards that cannot handle stress like Arduino branded products.
Why not help the actual developers that made electronics prototyping possible for everyone?