I bottled this recipe a few weeks ago and to anyone looking to try this, these are my notes so far.
I used the 750ml of malibu, 2 cups of appleton and 2 oz of sugar to prime with, and it's a little over carbed, but no bombs or anything, but i do need a very tall glass to hold all the foam. So maybe try 1.5 oz or 1.75 oz of sugar and it should be close to perfect.
Week 1 after bottling,
For taste i find the appleton flavour kind of overpowers the banana to me, and i remembered after tasting that i don't like appleton rum, so try appleton before and see if you like it, if not substitute for something else.
I'll be honest, week 1 tasted bad, i thought it was going to be 5 gallons of gross, but i'll give it time.
The strongest taste was still apleton, but it mellowed out a bit to be drinkable, still don't notice much in the way of banana flavour, but there was something else in the background(i assume the malibu)
The appleton flavour has mellowed enough to not be recognisable as appleton, the other something else flavour is mostly gone, still not much banana flavour, but it has a bit of a molassasy taste, i assume from the rum(since it's made from molassas) but good enough that i drank more than a few.
I'll try to update this as i go, but i'll give it a few weeks before i get into it again.
At this point though be careful, i made the mistake of drinking 5 of these in the time i would normally drink 5 regular beers, which amounted to me chugging 10 beer in a relativly short period of time, which brought the usual effects of talking loudly, swearing a lot, not being too steady, then hiccups and a headache the next morning that just wouldn't go away.