Do you only have access to the backyard for positioning your station? Or can you put something on the roof?
Where do you plan to put your anemometer? The VUE is all in one, so your rain, temp, wind is all going to be in the same place. The OS you can put your anny, rain, and temp in three different spots to rule out wind and rain shadows. With VUE you are either on the roof with everything, or in one place in yard with everything.
If your ~300 has a hard ceiling the Vue will run $386.95 (vue sale price $269, low price quote for weatherlink 117.95) in order to get it connected to your pc. OS will just cost you price the listed of $189.95 and a serial cable to connect (few bucks)
I have a vp2 now, but my OS 968 is still kicking after 4.5+ years, only issue was humidity sensor (which unlike others I killed it, not faulty), but a $20 replacement and it works fine. While Davis has far superior customer service, the number of Vue issues raised here are far more than I have seen over the years with Vantage Pro 2 users. New product growing pains I assume. Although even with my VP2, I already had to replace, ironically enough, a humidity sensor....)
Good luck with your decision.
Andrew