sensop - Some good questions there.
The .308 versions are not really the same rifle - its a bigger version all the way around. I dont know anything about the .243 variant. .223 is a good round for many applications. Just not for Deer.
Armalite is a good firm. They make good good guns.
ARs are generally pretty good - but they can have quirks. Love them or Leave them.
Though right now I would be willing to trade mine straight across for a folding stock AK-47 and call it good.
Well... depends on the AK...
ARs are easy to work on and I got mine fixed in about 1 minute. They can be as reliable as you make them... Like a marriage.
"A fear of weapons is a sign of retarded sexual and emotional maturity." - Sigmund Freud