+1 to BS.
I have a saber cqb, 399 at UCT. 10.5" would be my recommendation, but if you like long guns then 14.5 works too.
If you plan on changing your rail later, just get the basic fighter.. you'd be changing your stock[?]/rail anyways.
VR are based on M4's.. they are just replacement name for their "E" series.
lots of reviews for retailers online, just buy where the price is the best... and then research if the store is legit.
UCT is legit if you're wondering.