I haven't tested it in Elves because the reasons you provided are enough for me to think its the weaker alternative (in Elves case). We are vulnerable to removal / easy board wipes as it is, lets not add another card to that. Additionally, sometimes we want to Pithing Needle ASAP, for example if you have no discard and are vs a storm variant. Even Miracles is something we want to make sure Needle sticks targeting SDT, rather than lose Revoker to STPS / Terminus / Supreme Verdict...and then they have access to SDT again. Additionally, against UWR I'd rather have Needle as its harder to get rid of, whereas they have 8 main deck answers usually (Bolt/STPS) just to get rid of it, in addition to any counter you have to pass up.
Of those 3 MU's, 2 of our hardest (Miracles + UWR), with the other (Storm) being a race slightly in their favor.

