I really like light rails but of course there advantages and disadvantages to using them.
The benefits of using one is you don't need the safety glass for the reflectors since the lights are moving, "which glass gets dusty which in return reduces lumens", no need air cool the reflectors, and you cover twice the footprint with one light.
The disadvantages, it does take a little longer to flower around 5-8 days from what i have seen, the buds are not as big, cost of the rail, cost of fans, ducts to cool the light, since the light rail can cover the same footprint as two lights add the cost of a new ballast, bulb, and reflector.
To each his own iv seen a buddy go from 13-14oz with one 600watt, 20oz and his setup was far from dialed in. So im guessing once he gets everything running up to par I dont see how he cant get 23-26oz.
Also I couple years back had a buddy doing an ebb n flo with a 1000watt on rail covering about 50 plants and got a little less then 3lbs.
If you room is dialed in I sure as hell would rather take smaller buds but more of it then less with bigger buds. I personally dont really care for huge buds, i like the little 2-4 gram side buds more but thats me.