If you are connecting buildings and spending this much money, Invest in the proper media converters and go singlemode.... multimode at gig or 10 gig si really a apin in the ass over 500m, and you havent mentioned the distance from the outside area to the telco rooms on each side... Singlemode is cheaper anyways....just the active stuff is twice the price, but a bizillion times the speed possible for the future!
