Good trade. Each costing right around a C-note, give or take, depending on used status and source and any extras. But it's apples and oranges after that. If you'll get use out of the BK2 and value it more in the using, then it's a great trade. But it's like trading a Corvette for an F150. One is for speed and handling while the other can haul lumber. Both are great vehicles.
Without the coating, yes, it will rust, like any carbon non stainless blade. But a lot of us here spend a lot of time getting that coating off and putting a patina on our Beckers. Lots to read on that score in this forum. Use it, clean it, dry it, and oil it and it will stay rust free and develop nice character.
It's a trade I'd make, though. The knife, not the cars.
Zieg
FWIW, here's my BK15 with no coating, carried in a leather sheath, and used most days of the week on a horse farm in all sorts of weather. Some kitchen use, too.