you may not be able to charge your batteries. If you ran the line from the alternator through the isolator, and the isolator "locked you out" or failed HIHO, you might fry your diodes if your alternator doesn't have a battery.

I think in general, having redundant "stand alone" systems is better than having potential "bottlenecks" in the system. What's a little wire and a couple of hours worth to you?

I've had one of Andina's combiners on my current and prior boat for over twenty-five years. They've worked flawlessly, though with my current Mastervolt system and Ballmar smart multi-battery battery regulator/controller the AC and Alternator charging makes the combiner somewhat "redundant". It still "clicks-in" and "-out" as the voltage threshold is reached. ;^))))