Hearthpwn

I've been using Swarmadin since early beta because it was/is just a great, easy to play deck that uses nothing but Basic cards.

I still win with this deck at a fairly high rate, but now that I have some cards in my collection, I'm wondering if I should try swapping some cards out for upgrades.  Any ideas?  I'm sure others have experience upgrading from this deck.

Since you're running a lot multi-spawn minions then a Sword of Justice would make them even more powerful.  It's an epic, though.

Chillwind Yeti is a good card, much better than Ironfur Grizzly unless you're just really wanting the taunt.

I'm pretty sure the Grizzly's are there to protect the weaker multispawn minions earlier in the game.

Loot Hoarder may work better over Novice Engineer.  Bigger hitting power, but can have your card draw killed with silence.

Problem is that this deck really wants those token creatures in play and most of the expert cards won't fill that need.  You end up removing tokens for utility.  You start adding more utility in and you change the dynamic of the entire deck.  For instance, Frostwolf Warlord becomes rather crap without the token generators.  Remove the tokens and you may as well remove Frostwolf as well.   Now you're no longer swarmadin.

Sword of Justice seems like it would be a good add.  You will weaken your burst for more sustainable presence by doing so though.

Would swapping Novice Engineer for Acolyte of Pain, 1 Acidic Swamp Ooze for Defender of Argus, and Sen'jin Shieldmasta for Silver Hand Knight be positive changes to this deck?

Actually Silver Hand Knight would be an excellent add for this deck.  Forgot all about him.

The rest seem like they would be pretty legit as well.  Acolyte at worse will be silenced and at best will draw 3 cards instead of 1.  You usually get 1 off him no matter what.  He also works well with buff minions and Defender on Acolyte is always fun.

Honestly, the best way to improve paladin aggro imo is to... play warlock. Not trolling, that's just a fact.

Anyway, if you want to stick with paladin there are a lot of improvements that you can make. I'm a bit confused, since if you've been playing since early beta you should have a lot more cards. If you have some of this commons and rares add: Knife Jungler, Defender of Argus, Divine Favor, Argent Squire, Argent Protector, equality, aldor peacekeeper, noble sacrifice and one avenging wrath or sword of justice (epics).

They could replace a lot of your creatures which are very inefficient and could be taken out without hurting your deck too much: Dragonling Mechanic, Ironfur Grizzly, Lord of the Arena, Murloc Tidehunter, Acolyte of Pain, Raid Leader, Razorfen Hunter. If you deccide to go with the Divine Favor theme also take out Stormwind Champion and Frostwolf Warlord, since they're high mana cost makes them prohibitive in that kind of deck.

Lord of the Arena could be replaced with Sunwalker quite well.  Sunwalker is a pain to deal with.

Wait... what? No Imp Master? Violet Teacher? You may even add 2 Noble Sacrifice instead of the bears, to get more tokens out of the teacher, they will protect you anyways and are cheaper to drop down.

I think Raid Leader is a bit too weak to aoe, so you could try 1 Master Swordsmith if you have it, as he survives most 2 damage aoe.

Also second Defender of Argus, two Knife Juggler, and 1 or 2 Argent Protector would look really good in there.

Hammer of Wrath would also give you a token with the teacher.

Made some drastic changes after I was able to craft some cards (I didn't craft them specifically for this deck).  I think it's drastically improved from what I had.

I'm mulling replacing the bears, but I need them as a 3-drop, and I'm finding the early taunt they provide can be huge.  I'm going to test it with Harvest Golem (x2) to see if I run into problems without the taunt.