Personally, I'd wait a couple of months to see if the TSB really solves the problem. Lexus (which effectively IS Toyota) is quick to issue TSB's just to address complaints, but they don't always solve the problem. Cases in point are the 04 RX 330 dash rattles and the driver's window wind noise. TSB's were issued for both, but they didn't find the true cause for several more months and then the TSB's were re-issued.
Since some lube makes the clunk go away for a little while, I'd wait to see if the TSB solves the problem for longer than that. If the people on ClubLexus say it's solving the problem, then yes, I'd take the TSB to the Toyota dealer and get in line for the new parts.