Why not put the disconnects right below the meters? They are accessible right? You can get a single enclosure for all four meters and mains, a lot easier... all of the NEMA3 ones I have seen in the last few years have provision for locks on the covers to the breakers too.
[Linked Image from eatonelectrical.com]

Anyway, IMO 50a is a little light for an Apt. Definately too light for condo units. What if any ever need a 220/240 for anything?

Also running all of the services in one 2" may not be legal for your POCO after the meter section, not to mention derating conductors to 50%, per Table 310.15(B)(2)(a).

Mark Heller
"Well - I oughta....." -Jackie Gleason