What you are talking about...
But doesn't suspension geometry come into play as well? I had been told that if you move where the centerline of the wheel is it will negatively effect handling.
is changing the track width. In very general terms, increasing track width (moving the tires away from each other) is better for handling, although there are far too many variables to say that this will be the case with every car. Dallara X1/9s and many X1/9 based race cars use a greater track width. My race X has a greater-than-stock track width, and the combination of more track and wide wheels can make it somewhat darty, but it can take a corner faster than a stock X, so as with most things, it's a trade-off.
One negative effect that changing the track does have, is that it is harder on the wheel bearings. If you have a non-stock track width, you will want to keep a close eye on your bearings.
But if we go back to the formula of more positive offset (deeper backspacing) and the use of a spacer plate that is equal to the offset difference (between a stock wheel and the new wheel), then you will not alter the track width by much. Of course, that assumes that you use the same width of wheel. If you run a 6 inch wheel with the same backspacing as your stock 5 inch wheel, then you will have effectively increased your track width by an inch... it's all related, and no one can give you a positive "yes it will fit" or "no it won't fit" answer on the internet, unless they have done it with the same wheel, tire and suspension setup. Even then, car to car variances may come back to haunt you.
Best to stick with wheel widths that are close to stock (5, 5.5, 6.0 or 6.5 inches), decrease tire profile as rim size increases, and be very careful about measuring the offset and calculating everything out. Even then, no guarantees.
Pete