Regarding pumping loss, I think it does practically eliminate it, here's why. I hope the logic I have can be followed, cause once I figured it out, I was like, Oh yeah.
1st, keep in mind a deactivated cylinder has no pumping loss, if the valves don't open, the air in the cylinder just acts like a spring and returns whatever energy it took to compress it back on the next downstroke. We can agree on this. If you think otherwise, read
this.
2nd, following this idea, if you only let in enough air to operate at 30% power, then opening the valve till the cylinder is half full, then shutting it prior to when it would normally be, you in essence only pull in the air you need, you then essentially draw a vacuum on the cylinder at the bottom half of the intake stroke, and when you compress the half cylinder of air, you have the same result.
The advantage is, you pull in air for only half the stroke when the piston goes from zero to full speed then you quit drawing by closing the valve.....does this make sense, the valve is open when the air velocity is lowest, makes it to where the velocity is about to be at its max, and closes, so there is only a short time that the air is trying to squeeze past a restrictive opening, and this short time is actually very beneficial because it creates a lot of swirling to aid combustion.
Another advantage is the lower cam load, by only working half the time, the cam doesn't need as much power to turn it.
So to paraphrase, the valve at low load is only open at the top part of the stroke when the air velocity is low, so low loss, then for a brief moment there is a high loss/swirl producing intake, then you're back to no pumping loss because the valve is closed, and whatever pressure differential occurs during the bottom half of the stroke will not be a factor.
In my mind I see this as being a way to vary the displacement of the engine without cutting off cylinders.
Hope this didn't further confuse and If I'm missing something I'd sure love to talk more about it cause I'm learning too.