I wanted a Length as short as i could go because i'm not old enough to qualify to fill out form 4. I will be filling out form 4 but mainly for silencers and probably one 11.5" AR build. I personally just really like the "look" of a 14.5 carbine or mid length versus a full 16. As for the funky flash hiders yes they do increase performance. After shooting my PWS SM556 I was amazed. The recoil was about like a .22lr. Which made it extremely manageable when shooting faster, and increased accuracy and realigning on the site. While that same day shooting my friends carbine 16" trying to actually manage the fire will keeping fast constant rate of fire, was rather difficult. Now that in part is due to carbine vs Mid length but the Flash hider helps. My FH also will accommodate a Gemtech halo silencer or Knight Arm Co. QDSS-NT4. I just like SBRs.