I see no point in playing LOMAC to get used to FC3...it can only misguide you as most of the featured aircraft systems (radar, EOS, HUD, SPO) evolved and are featured more realistically with FC3. IIRC there was a faulty gun pipper with Russian birds in LOMAC.
Oh yes, 6DOF cockpits and all the eye candy stuff is a huge improvement as well.
Unlike FC1, 2 or 3 LOMAC had no advanced flight models of Su-25 and 25T.
Same can be said with misslile and bullet performance, their trajectory and range are tweaked so both are now affected by gravity. It simply feels better now.
I dunno what exactly changed with radar system and flight characteristics of F-15C and A-10A since OMAC as I never ever flew any of them. You see, I got this thing with imperial units so when I see IAS of 140 at 1000 AGL during final I automatically throttle up and point my nose down!