If you build the deck first we may be able to give you a more in depth opinion. From my standpoint there are two things I see:
1)
Monastery Swiftspear - is a low drop creature, it has haste right out of the gate, and only costs one color to play.
2)
wee dragonauts - it is still a relatively low drop creature, it has a higher toughness, it can fly AND it becomes stronger than the swift spear.
So basically the
wee dragonauts are the stronger of the two buts it's slower to get out. If you're playing U/R then it won't be a problem cause you'll have
goblin electromancer to reduce the costs of your other spells and 3-mana will be a cake walk for you.