Most Helpful Guy
When I'm single : I like it. That way I know if someone I like is available or not.
When I'm seeing someone : I like it. That way I know she's commited to the relationship and it will keep some guys who like her at bay.
But there are guys with commitment issues who might prefer to take it slow and low profile and might not like it so much.
So unfortunately, as most of the time, there is no single answer and you'll have to read your guy or just ask him if he's ok with you putting your status to "In a relationship".
Most Helpful Girl
I DO like to share my relationship on social media, but not obsessive. we may post a picture together once in 2-3 months, when we gave something interesting to share, from our traveling, or a special event, not just selfies, or every present, dinner etc. I think in this times it's fine to show a relationship on social media, but also to keep the private moments just for you