I've owned a few Vegas's and feel your pain. My 08's were notorious for backfiring with the swept pipes. I installed the S&S intake and download on 1 of them and the backfiring was very minimal. My 2010 Vegas with the 106 had swept pipes on it and did not backfire, I put the S&S intake with map and now it backfires. It is not bad but it is worse then with just the pipes. I have notice that people with 2010 Vegas's with the 100ci are not complaining as much as the people with 08's. They say there is no difference between the two models but I tend to not believe that.
As for the Lloydz Idle Controller this came up this weekend with a few of the riders I met at Biketoberfest. Three different individuals had them installed. Two of them swear by it the other said it made no difference. My dealers saleman swears by them and said it really works. I have no first hand experience with it so all I can say is it may be worth a shot. Who knows who installed the unhappy customers parts and if it was adjusted properly.