No, it should not affect the trimmer in any negative way. I guess you are assuming it would create a slightly lean condition? Removing it will allow it to flow exhaust only moderately better than it did when it was new and had a clean spark arrestor.
I choose to run mine without. But I guess if you lived in an area where wild fires were a pretty frequent thing, your decision would likely be different.
take it out it helps my equipment run smoother. Lawn equipment store said it shouldnt hurt equipment. The only problem is that you can get a few hundred fine in some states. It is really ment for California