Replying to myself to update that I've got one on the way. Shipping seemed fairly reasonable (for Australia to the US). Hopefully I can knock out all the other projects I have stacked up so I can get it installed quickly once it gets here.
A couple of comparisons between quiet and loud modes. The mic leveling on the phone doesn't do justice to the difference in volume between the two. Also the much of the louder sound gets washed out.
I still think nothing beats the look of the OEM pipes. However, I think Vandemon looks like it could have been original more than any other slip on option I've seen.
The dual modes is a big plus for me. The loud mode is louder than I'd want to have full time. The videos don't come close to doing it justice.
Really the only downside so far is that, yes, they were crazy expensive.