Still surprised china hasn't replicated the xmitter extreme lineup of dual row 5W'ers... looked into this myself, comparing vX xmitter xtreme vs evo prime...both $999
21" dual row...... 36 LED's x 5W = 180W
20" single row.... 12 LED's x 10W = 120W
Same price for both bars, on paper dual row put out another 7,000+lm. I have a knockoff EVO (8*) bar to compare to my XE(10*), the 10W's 8* is obviously a tighter beam, but the 5W bar throws as far and in addition its close range light bleed spread was as bright as my other 30" bar with 3W 30* LEDs... IMO only reason I can see running the 10W over dual 5W is if space was limited, but were talking barely an inch difference...