It's not quite as simple as swapping out one solution for another. Much depends on the type of battery your second battery is (or maybe will be in the future). The alternator on the 80 series isn't particularly smart which means it is only any good at charging flooded lead/acid battery starter battery. The relatively small amount of energy that is used to start the engine is easily replaced quickly by the alternator. However if your second battery is a deep cycle marine type battery that often is used when the engine is not running it will take ages for the alternator to charge it. Flooded batteries are not efficient at absorbing charging current. That said, I used a blueseas ACR system for years which worked well as I was camping during the night and driving during the day. I was very conscious that in winter months were the driving day was shorter, the battery rarely made it through the night (mostly running a fridge).
Depending on your application, investing in a Redarc BCDC1220 would be a much better solution. It has the smarts to adjust charging to match the battery type and can also handle a solar input if you choose. It is more expensive than the ACR but no need for AWG0 cable runs between the batteries. Also switching to a AGM type battery will give significantly more available stored power. The AGM batteries have a much reduced internal resistance so they accept a higher charge more efficiently (about x5 more efficient).
Lots to think about.
Depending on your application, investing in a Redarc BCDC1220 would be a much better solution. It has the smarts to adjust charging to match the battery type and can also handle a solar input if you choose. It is more expensive than the ACR but no need for AWG0 cable runs between the batteries. Also switching to a AGM type battery will give significantly more available stored power. The AGM batteries have a much reduced internal resistance so they accept a higher charge more efficiently (about x5 more efficient).
Lots to think about.