The unscrewing "problem" would only be a problem if you have a two piece guiderod. A small amount of plumbers tape will keep it from unscrewing. If you have a one piece guide rod dont worry about it. I put full length guide rods in all my 1911's. The one piece rods are usually a little long and require you to remove (abrasive wheel, buffer, dremel, etc)a little of the muzzle end of the rod off for it to clear the bushing.
There are usually debates over the functionality of FLGR's. I dont buy the "John Browning didnt put one on there so it doesnt need it" argument. Browning didnt put extended saftey and slide release controls, beavertails, hex head grip screws, novak type sites etc. on there either, but those items have become commonplace and accepted on many 1911's. These items along with the one piece guide rod issue is a matter of personal preference.
I have had a spring bind with a non-FLGR gun. I have had gun group better once a FLGR was installed. If you've got one, dress the muzzle end and get it in there, its not going to hurt anything.
Edited to add: If you happen to have a mercury filled or spring loaded guide rod setup, I'd be a little more careful with how much of the end of the rod you remove. There should be enough metal in a well made rod to allow fitting. Remove just enough metal to allow installation of the bushing. This can usually be done by removing small amounts, checking for fit, repeat - you get the idea.