... and since it stacks with Expertise, it projects deep into ZOMG TEH BROKENZ territory by 11th level.
Cheers, -- N
Why 11th ? Neither expertise nor draconic spellcaster change from 5th to 14th, so its not really until 15th that it starts to get a little broken.
I say a little because while it was obviously a mistake (should have just been a flat +1 to hit... and so should the eagle eye goggles), it still leaves implement users less accurate than weapon users (even leaving aside all the highly accurate weapon vs NAD powers) most of the time, so its only really an imbalance vs other implement users.