A retarded wombat could tell you that if the mains pressure is 2.7 bar and the pressure reducing valve is set above that, it'll make absolutely no difference which side of the p.r. valve the cw is connected. A "balanced" output would be worse than a non balanced one, because of the inevitable resistance-pressure loss in the valve.
If your mains pressure were 7 bar andyou had a prv set to 3 bar, then yes, your hot and cold would both be 3 bar.
But. There is also a non-return valve in the "combination valve" and there is a bubble of air in the top of the Megaflo. That means that your megaflo charges up to the mains static pressure - after a while. Then when you call for water (HOT ONLY) you get it at full pressure , not reduced by pipework up to the megaflo. This makes your supplies UN balanced. Over time (minutes) the hot pressure will drop to what the mains alone can provide, via the input pipes. Hot and cold will then be the same apart from the pipe resistances.
The Bubble can be added to, and you can use a buggun for the cold water, before it goes into the Megaflo. The thing is a Pressure Vessel, with a few bits added, generally called an Accumulator. If you stooge around the net you'll find them.