Recently window shopping at RRA (Rock River Arms) site and saw several sweet deals on their LAR-15 Elite Operator 2, and Entry Operator 2 rifles. After reading the basics for AR's...I don't know which rifle would be better suited to my needs. The only noticeable differences(and these may be HUGE!) is that the elite op 2 has a mid--length gas system and DOES NOT have the m4 barrel. Any ideas which is MORE important, gas system length...or barrel configuration? Which, if either, would you buy...for $1000.00 shipped with choice of rear-sight assembly, it seems like a great deal. oh yeah, which rear-sight assembly is best...I don't have a EO Tech optic......yet.