Theyre rare and short-printed, but not extremely so
For example, if players A and B each control a Shay Cormac and player A has put a bounty counter on player Cs creature, both players A and B will put two +1/+1 counters on their respective Shay Cormacs when that creature dies
Dominaria, Innistrad and M12 all provide solid cards that can fit in most decks, as long as you disregard the cards that depend too much on synergies (UR wizards,Burning Vengeance,Tribal cards from Lorwyn, etc.)
Still, I think it could use at least one more ability to make it a more interesting commander
In the past two years or so, these questions have become more common, especially as English card prices continue to skyrocket and collectors find it harder to buy new sets at MSRP