The 2 x 2 Metalux troffer claims to have 4200 lumens at a color temp of 4000K.
The 2 x 4 Metalux troffer claims to have 4700 lumens at a color temp of 4000K.
The price is $55 for the 2 x 2 and $ 65 for the 2 x 4.
I replaced a 2 x 2 in the library portion of the basement and a 2 x 4 in the shop side of the basement. The 2 x 2 replaced a 2 bulb (bent bulb) fixture. The 2 x 4 replaced a three bulb fixture. Both have more light than the fixtures that they replaced. The reason behind the replacement was a test to see if a LED fixture would generate less RFI for the FM radio stations that we listen to.
The experiment was a success. There is little or no RFI with LED fixtures as opposed to the fluorescent fixtures. The extra amount of lumens was an added benefit.