I don't know how you'd know for sure w/o bench testing both of them.
I know when the Vibe 1200D was released several years ago it did 1262w at 1 ohm 14v. The benchtest results and charts are still posted at carsound. The 1800D is just the 1200D slightly evolved.
I THINK I recall seeing a benchtest on the 1400D of ~980w at 1 ohm - 14v.
Long term I think the Opti's a better amp, but if you really want the extra couple hundred watts I guess the Vibe's the winner.