Hi,
I recently purchased the Balu regular and XL mutes and they are fantastic. I also have alot of experience with the Trumcor and do not believe it compares. The XL Balu is dead on pitch wise and has no problem responding in any register on my Nirschl. With the movable corks it is easy to get a good fit for any horn. They are somewhat more fragile than others on the market. For that matter so is the Trumcor.
Pete