As stated, in a bullpup design the extra length presented by a 16" bbl would generally be unnoticed. IMHO, a 16' bbl would save problems for many end users in the U.S. It probably wouldn't be a deal breaker for me, but it would definitely be a factor in my choosing a SCAR, ACR, Tavor, etc., so my votes goes for the longer barrel w/removeable FH. I bought an AAC Omni can primarily for the feature of easy QD mounting on any of my 5.56 rifles fitted with an A1, A2 or SOCOM FH.