Out of various Dark Horse luxury upgrades, this sure is one.
To be fair, it's not a bad upgrade - a cost of 2 instead of 3 means that if you plan ahead with Madame Labranche, you can play this in one turn once you're able to keep Dark Horse flowing. In addition, the ability to ready the card when you fail means that you can commit cards or use other boosts to make a second attempt after you've spent your resources on the first one.
That being said, this doesn't particularly push the boosts or efficiency of Mariner's Compass beyond the baseline, nor does it gain anything which would push it to the (admittedly high) level of Fire Axe. This works fine as a luxury upgrade for the Dark Horse package, but it's still very much a luxury upgrade. If someone didn't want the level 0 version, I don't think this gives enough to make it worth taking in comparison.