I've been really impressed with Phyrexian Metamorph recently while running two in an espresso stax build. I'm finding that I use Metamorph a lot more than I ever used duplicants. Duplicant had a bad habit of hiding in my hand because I'd be a mana short when I needed him (worsened by sphere effects), or I'd hold on to Duplicant in anticipation of a big threat that may never come. Metamorph, on the other hand, stays consistently within my mana curve and is a lot more flexible while orchestrating threats. I can defensively hold Metamorph when I fear BSC, or use him offensively to copy a target like Lodestone when all I need to do is keep an opponent on the run. While the exile feature of Duplicant is unmatched by Metamorph, Metamorph's flexibility really does make him a practical (and cheaper) alternative.

Also, in my experience using Duplicant – his greatest successes have been in Welder decks.

Meta has been pretty broad. The deck has won and lost against everything from workshop to dredge to oath to adnauseum. It's generally proven to be a versatile deck against a lot of match-ups, although the bane of none.

For big post-board removal, Weirding is the ticket. It's saved me a couple times against Oath. You can fetch Weirding using Matron or Recruiter given that its a goblin spell. While Weirding is far from perfect, its come through enough times to have proven a solid value. Generally though, my most common problems are the little dudes who get in the way of Lackie and Instigator, which is the reason for running a full place-setting of Fanatics. A Fanatic's one-damage potential is a huge disruptor, and their self-sacrifice ability makes them very strong against Dredge.

As for Workshop... ha, that all depends on the game – and generally the outcome of the first turn. Lackies and Instigators are great against Sphere because they circumvent all casting costs. If you can get an Instigator through second turn and search out some hate, you stand to hold some board position. The main-deck combo for artifact hate is Kiki-Jiki and Tuktuk Scrapper. By copying a Tuktuk, you trigger ALL Tuktuk artifact kill abilities... so two Tuktuks destroy two artifacts and deal 2 damage (each) in the process. If you can copy Tuktuk on both your opponent's and your own turn, then you get two artifact kills on your opponent's turn and another three on your turn... that's five artifacts killed and 13 damage dealt. Not bad. Board in some additional artifact hate, and you've at least got means to stand your ground.

Overall, while this deck has its unique challenges against the meta game, I don't necessarily see it as having excessive handicaps beyond what most decks face. While I don't think it's a top-tier deck, its holes aren't necessarily bigger than other decks – its power plays just aren't as strong. Again, you've got to keep in mind that the key player here is Earwig. If you can dispose of an Oath deck's standard three monsters, or an Adnaus deck's three tendrils, or remove a Time Vault and two Tinker targets from the equation, then you've already covered a lot of distance toward holding the board. Generally, Earwig is your single most important and aggressive play, with all other pieces just acting as aggro-combo support. While Lackies and Instigators are awesome, I'd gladly sack them to a Prospector for the sake of making a bigger and better play.

My friend Joe set me onto Instigators and Earwigs when I first started experimenting with goblins. I put together a list based on his recommendation, and over time and testing my list has grown more and more similar to his. At this point, we run about the same deck with just different priority put on Kiki-Jiki versus recruiter (I'm heavier on recruiter)... Also, I think he also runs a Warchief. I'm not sure how our mana base compares. Here's my current working list:

4 Goblin Lackey
4 Warren Instigator
4 Mogg Fanatic
4 Skirk Prospector
4 Earwig Squad
4 Goblin Ringleader
4 Goblin Matron
3 Goblin Recruiter
1 Kiki-Jiki
1 Lightning Crafter
1 Tuktuk Scrapper
4 Simian Spirit Guide

1 Warren Weirding

1 Black Lotus
1 Mox Ruby
1 Mox Jet
1 Lotus Petal
1 Sol Ring

3 Mountain
4 Badlands
4 Bloodstained Mire
4 Scalding Tarn
1 Ancient Tomb

Board runs leyline, jailor, pyroblast, more weirdings, sharpshooter, gempalm, and some additional artifact hate.

Overall the deck has proven fairly solid, REALLY fun to play, and has made top-8 in two 20+ tournaments. While it feels a little weird taking goofy monsters up against some pretty serious decks, it's had a surprising way of delivering. The main power play revolves around prowling in an Earwig on turn-2, which is fairly consistent given the first turn drops, deck search, and availability of fast mana. While Earwig goes to work dismantling an opponent's deck, the lackies and instigators who are (theoretically) doing the Earwig prowl strikes are also busy putting together the Kiki-Jiki / lightning crafter / prospector infinite damage combo. For a three card combo, I've had good success getting it out within the first couple turns of the game (often times thanks to prospector's ability to sack non-essential goblins for mana). If you really want to put the pressure on while your opponent has a slow start, just recruiting Earwigs so you can draw and drop one per turn hoses your opponent's deck while building up your monster power. When all else fails, there's always weenie swarm. All good plays!