Mana Boulder

Artifact
[mana]T[/mana]: Add ten mana of any color to your mana pool.
I think I probably would in many decks. Doesn't slow you down at all the turn you play it (assuming you're not looking to keep a couple mana open, of course), but then you run the risk of not being able to play the card at any point in maybe 1/3 of your games (since reaching 10 mana can be tough, even in EDH).
If you answered yes to the question above, how much do you love Omniscience? I haven't seen that card basically ever in an EDH game until I recently put it into my new Melek list. Is my playgroup bad for not playing this card?