bro, mau tumpang tanya... got 2 prob

i'm using Dlink DIR-300 at home, router upstairs, downstairs signal PS3 detect <50%..

at office using cheapo aztech, room at the back got very low signal
need to re-correct USB wifi adapter placement everytime.

i read the Dlink manual it state Single Detachable Reverse SMA

should i go for 7bdi onmi for both cases, or upgrade to GL+7dbi Omni?

so if i used GL need to package with 7db omni?

from the GL picture posted, it got 2 antenna rite, so need 2 7db omni, or no need?

price as in first post?