Sightstone seriously needs to recharge over time like trinkets. It's honestly trash in comparison...
Basically, trinkets outscale sightstones at about 25-30 min because you can keep pressure/stay active in the field as long as you want while still keeping vision up, where as if you had sightstone and want to keep vision up you are forced to recall every 2-3 minutes...
I often find myself able to be active on the field for extended periods of 10+ minutes at a time(not all the time, simmer down), only needing to recall for important item spikes.
Thus after many games with and without sightstone, I've come to the conclusion that
just isn't worth it anymore..
I completly understand the value of having the sweeper to go with the sightstone but I still find the extra power in a real item and the continuous ward charges vastly outweigh it.
I mean, you are 40 min in to the game, and you ward around drag with a sightstone, but shortly after the enemy team tries to rush baron instead so you are forced to run to it with no wards.
Now if you warded drag area with trinket, and shortly after you are forced to run to stop a baron attempt, you will likely have a ward charged before if not during the contention fight.
But w8, theres more!
Depending on how that fight goes, there is a good chance you come out alive, and if your health/mana bar are good or can regen, all you need are some wards.
And thats when
kicks the living shit out of 
So please, be fair rito, let ss recharge over time.