I think Eventboard.io made a good decision to rebrand because at this point in time, Eventboard.io is a very weak (crappy in my opinion) .io domain name. If they would have had Meeting.io or Event.io or something of that nature, they may not have had to rebrand. I own several .io's. If I saw eventboard.io in a drop, I wouldn't pay reg fee for it. It is a horrible .io name. Think of eventboard.com... much better... but still not the strongest .com name.
Look at Customer.io or Park.io... now those are great .io domain names. 2 word .io's are not the way to go... at least not yet. I have seen .me .co .xyz....etc... but so far, .io has alot of great websites... that in my opinion will determine if .io succeeds or burns in flames like .me .co etc.
Of course... Teem.com is a great brand..... but they had to pay for it.