zipec

Well, who wouldn't!

And if you happen to run into blockers too often, try Fury Charm for trample.

Yeah, Reckoners are awesome, but expensive bastards. I would go for a budget with Mindsparker, still an awesome three-drop. I would play him instead of Guttersnipe.
Also, reconsider these:
* Guttersnipe with only 12 instants and sorceries
* Batallion guys with only 22 creatures
* Foundry Street Denizen with only 15 red creatures (Cackler instead maybe)
The numbers are not terrible, but still

Exactly, also about the less-color hexproof, I think that blue is the easiest to cut. GBW could work better than Esper. Maybe even pure Selesnya.

Nice deck, few suggestions:
Unsummon instead of Disperse (if I assume correctly its for clearing a way for creatures)
Fog Bank is imho better than Guard Gomazoa, it doesn't kill X/1 creatures but is 1 mana cheaper.
Charmbreaker Devils are powerfull but too expensive, consider Wee Dragonauts instead.
If you wish, take a look at my similar budget Izzet deck, it doesnt hit as big as yours, instead it focuses on burn and disruption to boost Kiln Fiend and friends. http://www.mtgvault.com/zipec/decks/ru-izzet-tempo-budget-modern/

Honestly, consider rebuilding it. Or wait for Theros.
The problem of aura decks is that they mulligan poorly and I am talking about 2-3 color decks, with your 4 colors and this fixing its gonna be catastrophic.
Also for standard consider less dedicated aura deck with more creatures. Note that you still have no protection from Supreme Verdict unlike modern auras with totem armor. You dont need everyone hexproof, namely Lazav with his awkward manacost and ability you can use only by chance is quite bad here. The Lawmage is probably better, he has evasion, but still he is 4cmc.
Also i dont like sphinx revelation. Its good spell but totally out of place here.
And the last problem - consider some removal for a deck as slow as this, you may be dead before you roll with the big guys.

Not bad. If I may suggest, play 4 Sentinel Slivers, imho he is the best sliver around :-) Also I like you not including black, 3 colors (or 4 tops) are enough for sliver deck. You included blue in very elegant manner that it doesnt disrupt your mana base (Shimmering Grotto / Manaweft Sliver), I like that. Maybe include some more removal, looks like you depend on 5cmc Thorncaster Sliver a bit too much to clear your way.

What exactly are you trying to achieve by this deck? In other words, what is your win condition? I recommend first sorting that out, then cutting it to 60 cards with most of the cards in 2-4 copies, not this many singletons.

And one more thing, Snapcaster Mage makes more than half of your deck's price. :-) He is nice, but his only targets are the 9 flicking spells. I dont think its worth it. Maybe in a deck like this you would make a better use of Archaeomancer because if you flick it, the spell goes to your hand.

If you want some other ETB enablers, try Galepowder Mage, Glimmerpoint Stag and Restoration Angel. I would prefer them instead of some of your instants.
Also note that Steel of the Godhead, while a nice aura, is (as every aura) anticombo with all the flicking you do here.
Other nice ETB creatures playable in UW are Stonehorn Dignitary, Mulldrifter and Solemn Simulacrum.
Also if I may suggest, play less singletons, focus more on the effects you want the most.
If you want to take a look at Venser/Enchantment/Angel control deck I use: http://www.mtgvault.com/zipec/decks/uw-angel-control-modern/

Nice, cheap deck. But you have imho way to much lands even for landfall. 24 should suffice.
You can run more equips in place of few lands.
Also you probably know that you can landfall each turn with Boros Garrison (returning itself into your hand) which alone should convince you to play at least 3.
Pyroblast is more of a sideboard material.
Also if you are willing to spend a few bucks on an awesome landfall guy, try Admonition Angel, she is so pretty and well designed. :-)

Fabricate is not quite the same, I can't search for Painter's Servant with Trinket Mage.
Sensei's Divining Top looks usefull here. Too bad its quite expensive, I wanted to compose this deck as cheap as possible (obviously except the two combo pieces which I can't replace). I will consider it, thanks for the ideas.

If you like Springjack Pasture and goats, how about you try Trading Post. Its other mode (discard) also enables Angelic Accord :-)
A crazy idea but a solid synergy I would say.
EDIT: Oh my, Springjack Shepherd also make goats, then Trading Post is must have :-) Yay for goat tribal!

The cards with 100 copies in sideboard are cards I think about. :-D The actual sideboard are the other 15.

It depends. I personally like bant slivers more, but its up to preference.

This will benefit from some ramp. You have very high curve. 3-4 farseeks would help.

Is a combo speed up. A card disadvantage in here.

You have already won or lost before you drop your seventh land in this deck.

Maybe more fixing? You have a lot of UU or BB spells.
Tainted Isle or Jwar Isle Refuge are cheap alternatives.

Good idea, I add one.