I am curious about a few things concerning ff rail systems.  I am looking at the new LaRue 7.0, as well as others.  I am curious as to what if anything the Larue does to the balance of the gun?  How much girth does the rail add when it is wearing rail covers?  I have a new upper enroute and am leary of having the fsb removed to put the ff on.  Thanks in advance.

I don't have any experience with the LaRue, but here are some things that apply to most/maybe all ff handguards:

All FF handguards are going to be heavier than the standard 2 part plastic handguards.

There are ladder type rail covers that do not add any girth at all.

The fsb is easy to take off, but if you don't want to do it, take it to a smith.  It is a very standard operation and it shouldn't cause you any concern.  What exactly about it makes you leary?  It may be stuck/difficult to get off, but the mechanics of the process is simple.

i am akin to KAC FF RAS types. i currently have 3; a short, an MRE and a long one. all but the shorty make the front end heavier but that is just something to get accustom to. the KAS FF RAS is great for heat dissapation and the panels help insulate too. i have big hands so the extra size is nice to have. if you like the M4 hand gaurds then you should not mind the FF rails size.