It depends on how much sweep you're talking about.
At some point, many bars with LOTS of sweep will angle forwards before initiating the strong sweep to keep from bringing your hands too far back. In which case, those bars will NOT shorten the reach like a shorter stem would. They only change the angle of the grips.
Bar/stem should be considered together. If you like the hand position in general, but want it closer, then a shorter stem by itself should work. That's more likely to be effective for what you want than trying to achieve the same thing by adding sweep to the bar, which you may not like for other reasons.
That said, if you don't like the hand position, and want to change the sweep, you need to consider what stem you will need to pair with it. You might try what you have to begin with to minimize the number of changes at one time, but realize there's a good chance you'll need to change stem length, also.
I guess what I'm trying to say is to only change the sweep if you actually want to change the sweep.