I think this is essentially an S-tier card, easily worth the 5 XP cost of admission and should be considered for a first campaign purchase/upgrade on most Dark Horse decks. Comparing to the original (most of these points are overlapping, but I think there's distinct points for each):
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It doesn't cost resources. The 3 resource cost of the original is fairly steep for a deck designed around keeping resources at 0. With this you only need to focus on having resource for other assets you want to play, hugely simplifying the design of decks which take this.
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You don't have to play it. Playing a card costs an action, so given Dark Horse decks are lean and tempo-focused saving an action is always nice.
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You don't have to find it. Similar to the above, Dark Horse decks want it in play as early as possible. Dark Horse itself however is not readily tutorable (Mr. "Rook", Eureka!, Captivating Discovery and Friends in Low Places all spring to mind, but can all miss as well either come with their own costs or at a minimum take up deck space) and while the class does have good card draw (Take Heart, Drawing Thin, At a Crossroads, Unrelenting) it's never going to be infallible. Having it there and ready to combo off is the biggest selling point by far.
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The stat boosts activate very early. It's worth saying you can online that +1 all stat boost from your very first turn with just a couple of assets (e.g. Mariner's Compass and Madame Labranche for example). Equally common resources sinks like Fire Axe make getting the universal +1 trivial in your first few turns.
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Permanent protects it from asset discarding treacheries. Everyone has had a moment where Crypt Chill has discarded something useful I'm sure. With this being a permanent card it's safe, which is great given its high XP cost and importance to this archetype of deck.
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EDIT: Good point from the below comments - it saves deck space. Level 0 Dark Horse takes up two cards in your deck, while this takes up none. With the pressures around deck building these days, it's definitely a nice feature.
All of this sets the card up as dramatically better than the original and a huge leap forward for the 0 resource archetype. In addition to Dark Horse staples (things like Mariner's Compass, Fire Axe, Madame Labranche and Schoffner's Catalogue - check out the level 0 Dark Horse page for wider interactions and more possible combos) I would say the addition of 1 resource masks in Hemlock Vale (Sparrow Mask and then off-class Mouse Mask, Fox Mask and Wolf Mask, ignoring Cat Mask because it's niche) and potentially the 1 resource Matchbox depending on your needs are all good ideas. Hemlock Vale also added in the pretty great Fire Axe •• and the pretty medium Mariner's Compass •• to boot.
All in all, I think everyone would love to play an investigator with +1 to all stats, and permanent Dark Horse allows you to do just that - potentially from your very first turn and without any install costs. It's a very, very good card!