I have an ePropulsion as yet unused, until this spring when the mothership is delivered and the dink set up.
Piecing together the scant information on the new Mercury, it comes with a .75KW battery but a 1kw battery is available. The ePropulsion Spirit 1.0 Plus has a 1kw battery. Run time on the .75kw is described as less than the 1kw ePropulsion, as one might expect. But it appears with comparable battery size the run time is comparable.
So if it tests out to have comparable run times, choices would come down to price, weight, ergonomics and overall design, and dealer support.
Price is unavailable.
Weight: The Mercury is heavier. It appears to have a beefier shaft assembly, that may well be unnecessary in a 3.5hp motor.
Ergonomics and design: The Mercury breaks down differently, with a heavier shaft / mechanical assembly, so that if the plan is to launch a dink then attach the motor that would be harder with the Mercury. On the other hand, the Mercury transom mount detaches and one can attach the mount, and then attach the shaft to the mount. That's different and I guess I'd want to see how well that works, and whether it creates any advantage. Then, the battery sits covered by a hood and it appears electrical connections are thereby covered, which MIGHT present some advantage.
Dealer support: Torquedo has locked up a lot of the marine gear dealers so there is a good number of options for both purchase and parts. I have found there are very few ePropulsion dealers around, and I found it difficult to get delivery of carry bags for storage (took about 5 months), and that creates questions on repair parts availability in a pinch, like a new prop. One can only guess what the Mercury situation will become.
Bottom line, from what I can see the Mercury brings a different configuration to the table that might appeal to someone, but with comparable batteries it won't likely deliver more function, and that's no surprise.
I only glanced at the boat being announced at the same time. But its a 13 ft hard boat configured for fishing, with standing areas. A bit long to use as a dingy (for me). Its comparable in weight as a similar size Whaley made from the same material. I've seen no spec on carry weight capacity. Not a bad looking little boat, but for dingy purposes there are other hard dink choices out there.
Interesting new option on the motor. But no compelling advantage that is a game changer that I can see.
My two cents.