If you can find an FN FAL in the configuration you want at a price you can afford then you have the best of both worlds. It will perform whatever task you desire and it will be a good investment. However, that's the benefit of DSA, Gunplumber (ARS) and similar vendors/gunsmiths - they can give you exactly what you want at a reasonable price and ensure the gun runs every bit as well as any FN FAL you care to mention. No copy will ever have the investment value of the original but then you never have to face the fact that using it will consistently decrease it value to everyone else.
As a former owner of a G series I was faced with this very dilemma when I got back into FALs a few years ago. I wanted to recapture the original, but not at $7K-$10K. So I bought a friend's DSA built para for a very good price, then sent it to DSA for them to convert to their Congo configuration. Here is the result.
http://i568.photobucket.com/albums/ss127/cprher/FN%20FAL/guns001_zpsba17511b.jpg
The gun performs every bit as well as any FN I've ever shot, is very accurate for a small carbine with iron sights and takes up very little space. With the money I saved I was able to build two others: an Israeli clone and a scoped FAL, which was not meant to copy any particular configuration. It's only purpose was to be as accurate as possible.
http://i568.photobucket.com/albums/ss127/cprher/FN%20FAL/IMAG0029_zpsfa5eff7b.jpg
My total investment was less than the $7K entry price for the G series I used to have. In my opinion, that is a very smart investment. I got EXACTLY what I want, can shoot them at will without any undue guilt and can turn around and sell them in the future without any problem.
Keith