There is no doubt that there is a bit of extra noise because of the sting tracker.
I have made two bad shots with mine and about a dozen good shots in the last year. One was on a bear at 10yds and I am fairy positive that the string tracker had nothing to do with the shot being bad.
The second was a doe about a month ago. She was semi-alert but very close and I hit her real high. I do not know if she ducked or I just shot high or if she reacted to the extra noise from having the tracker or if it was a combination of two or more of those things. She is still alive and I am still gunning for her. In that same time I have shot one doe and 3 differnt pigs that were all very good hits with very poor blood trails. The string tracker really helped me find all of those critters!
Bisch