My general opinion on Focus:
I like what DE tried to do with Focus 2.0, really. However, it still needs huge improvements, but I still think the frame of the mechanics are nice.
Imo, Focus should be viable to be used in an "Operator alone"-fashion AND at the same time be able to be fully complimentary for your Warframe useage.
Penalties in something as requiring as Focus is also a total no-go (thinking of the energycost increases mainly). Many of these mostly apply to Void Mode up