Butch I ordered the 320D 2 bank to put on my stick steer boat a few years back. I ended up returning it for two reasons. First it was really heavy compared to the BPS charger I had on my previous boat. I'm talking 4 or 5 times heavier and I didn't want that extra weight hanging on my transom, which was the most practical place to mount it.
The killer was it didn't load share. Mine was a 10 amp two bank charger and it would only deliver a max of 5amps per bank. The 10 amp BPS would charge based on battery condition. So if the start battery was 100% charged it sent all 10 amps to the other battery.
I went with another BPS charger even though it was 20% higher cost. (The 320 was on a great sale).
I know there have been some knocks on the BPS charger, but the one on my 2001 Tracker worked flawlessly until I sold it to Gerald Cromer and far as I know it is still going strong.
I'm guessing the more expensive MK has newer microprocessors and has similar features and weight to the BPS unit.