You will probably get a lot of "don't do it"s on this one.
And while it is true that wheel spacers but more pressure on bearings, I have never heard of an engineered set of spacers causing a problem.
What do they do?
They lower the roll center of the car.
And they also have the effect of changing the camber center.
On of the problems with my Z3 is that there is no rear camber adjustment and the rear end, like many RWD cars, wants to come around. (Like the old porsches, you have to drive the Z3, a concept that many do not understand and few can actually do)
Well, there is an industry accepted fix which is to use H&R (german suspension company) Wheel spacers on the rear only. No one even knows someone who has had suspension problems from doing this and it makes the Z3 a completely balanced machine.....depending on how much spacer you use. 25MM plants the rear so much that the balance shifts to understeer. I run 10MM which still leaves the car a bit tail happy when pushed, but I like it that way.
Putting wheel spacers all the way around on the Murano will also lower the roll center but I haven't a clue as to what it would do to handling.
Flatter in the corners? Most certainly.
Oversteer or understeer? Probably.
I would suspect that if you never explored the Murano's handling at the limit, you would only feel the roll center effect and you would like it. BUT. If you inadvertently explored the outer fringes of the Murano handling by turning into a decreasing turn off ramp at high speed, you could kill your self if the spacers made the rear come around unexpectedly!
I've said quite enough here.
The bottom line is that nobody knows what putting wheel spacers on a murano will do.
But the "dangers" to wheel bearings etc is greatly exaggerated.