Battery prices have come down, and the segment of 12V drop-ins has exploded since the EP Carry was first introduced.
The dedicated 24V battery was expensive then, but it's ridiculous now. With the offered boost converter, you add one of these 12V replacements and you have several hours of motoring.
I find the original battery sufficient for nearly all uses except if you are becalmed on long cruises. Here's an
example. While that situation looked dire, it turned out, it was a false alarm.
However, I'm strongly considering adding a 100Ah 12V battery to get 1200Wh, compared to the 9.6Ah 24V battery's 220. Even with some conversion loss in the boost converter, that's around 4-5 times the range. That should make adventures like the one I subscribed possible even if the wind doesn't come back. However, if I was trying to sail an event like the Texas200 with its 50nm stages, I'd bring a 200Ah battery (and a solar panel) to be able to motor at least 1/2 stage per day, plus power some devices. (This year, the usually reliable wind failed, but even people w/o motor managed to complete, those that persevered).
For such extreme distances, I might possibly invest in a slightly more powerful electric motor, because at some point, after a few hours of this, being able to do 4.5 or 5 knots will test your patience less than doing a bit over 3 knots. Again, for shorter distances and as a backup that you expect you won't actually need except as a last resort, going a bit slower is better than not going. However, I *really* appreciate how light the EP-Carry is, and how you can operate it from a sailing (not a motoring) seating position. So, even then, I might opt for a light weight solution, with the idea that the weight penalty applies constantly, but the limited benefits only apply in very specific circumstances.