Had the same issue on my 2006 Tahoe with a 5.3. I purchased it from my Dad about a year ago. After talking to him (he had it for about 230k and the lifter tick occurred around 40k) I got a better picture of what was happening. It would happen during the colder months in the morning upon startup then oil circulation (suspected) would properly lubricate "faulty" lifters. I did the same research and read the TSB from chevy as well as talking to a dealership. The dealer wanted to do about a $3000 dollar repair by replacing lifters and camshaft. Seeing as that is most of the cost of an engine and the engine has been running for more than a decade with this issue I opted against that. I watched about a dozen youtube videos and saw a bunch of hokey fixes that didn't seem to help anything in any permanent sense. After doing the second oil change my oil pressure completely dropped and the tick got even worse (further verifying at least to my specific issue the thoughts about oil pressure effecting the lifter tick). My dad had used conventional oil for the entire life of the vehicle and I decided to try out full synthetic. I gather due to the difference between the conventional and synthetic oils and it being the second oil change that it changed the inner characteristics of the "gunk" build up on a high mileage engine. Once again this is conjecture from me that I have only my modest mechanical knowledge to base off of. I work with industrial process equipment and so its not a direct knowledge that I have but what I have experienced with "similar" process equipment. So to continue the narrative I had lost oil pressure and the sound was significantly worse. I knew it was necessary for a fix to occur immediately. I opted for the pickup tube o-ring and high flow high volume oil pump from melling. I accomplished about 90% of the repair down to the removal of the oil pump but was unable to remove the oil pan with out dropping the front diff. I had my mechanic buddy finish the repair after having a similar disagreement about bearing clearances and that a oil pump won't increase the oil pressure per se. I listened to his point and I understand what he was talking about the wear of metals over a life of an engine and the clearances increasing but as it was a cheap fix to possibly extend of the life of the engine I went with it. Low and behold after the repair (I opted for the higher pressure springs not the stock) the pressure sat comfortably around 50-55 psi at idle and 60 plus on the highway. Previously the pressure gauge would hardly budge whether it was at idle or full throttle. I conferred with my dad and he confirmed the same issue of the oil gauge but assumed it was "normal". So just to chime in that it can fix the noise and potential damage that can occur from the lifter tick (I have seen some engines stripped down with the tick and saw the possible damage that can occur on the camshaft). I can definitely agree that if the engine has increased clearances or lower engine knock that its a ticking bomb regardless of the repair but for the case of the lifter tick it can eliminate that (I have had the fix for over six months and not a peep or abnormal operation from the engine). But the conclusion that I reached for my specific issue was that it was worth the money because it was that or a new engine. So for the sake of practicality Im inclined to give this repair a nod. Glad someone else has done this too!! 
