I would be in for 1 of the adapters.
NB, also let us know what you find out on the stock. I would buy from you if you can get your hands on them.
I am so-so when it comes to the FAST and this looks like a better option for the XCR. One question, will this work on all versions of the XCR? I am assuming the design at the stock interface hasnt changed. Thanks.