Turning the targets into treasures is certainly a drawback since it gives players the option to turn their useless card into mana, but ironically players will often crack their treasure and lose the opportunity to get their card back when Kitesail Larcenist leaves the battlefield
$25 Upgrade +1/+1 Counters is a very deep archetype so there's more sweet upgrade options that I could ever hope to cover, but I selected some of my favorites: for protection I've added Bulwark Ox and Mutational Advantage, a bunch of proliferates with Metastatic Evangel and Dreamtide Whale being the two best, ramp got a massive upgrade with Astral Cornucopia / Kami of Whispered Hopes / Purestrain Genestealer / Summon: Fenrir, and so on
This card is incredibly powerful because even if its not going to net you a lot of cards, its going to force your opponents to play slower
In Commander, with 30 lands, that chance is barely there - 1.9%
All of the builds were really solid and tuned, and I even recognized the names of a few players that I played, too
Finally, you play it from Exile with Flashback, which will result in the card being exiled permanently
