I'm playing through anyway because the story appears to be slightly different, or at least have different arcs in it, based on having the cast of characters with you. I'm doing a playthrough with Astarion, Karlach and Shadowheart. I realise you can still get much if not all of these stories without having them actually fight with you (by just returning to camp to discuss) I do feel like I'm getting added story value by bringing these characters with me. Some things just seem to unfold while wandering in a way that makes sense. I wouldn't be achieving that value if I were in a full custom on my first playthrough.

If Larian drags their feet too long, or confirm that they never will do custom parties in a normal way (without the multi-client workaround) then I'll probably play through again until I've used all of the companions in my main party for the win.

At that point, though, when I would normally be doing all kinds of creative parties I'll probably just walk away from the game if they haven't implemented a suitable feature.