I don't see the problem as the Thunderbolt being inherently inefficient but rather the parameters set for mass notification having been a little over the top during the days of the Cold War: you can't track and predict an impending nuke attack like a developing storm, and if danger was determined to be imminent there would've been a very limited time window to take action, and the 'Bolt was about as unmistakable of a purpose-built noise maker as one could get.
Aside from its bulk, I'd consider the Thunderbolt to be a pretty versatile platform; you don't have to hunt down a matching stator if by chance a spare rotor happens to be a different tone combo from what you expect, and save for a few other examples, you generally couldn't rig a siren up for hi-lo without sabotaging something. Of course there's obvious alternatives out there now, but look at how far composite and fiberglass had to have come first to cheaply render a siren with no blower more effective than an old supercharged monster with twice the total horsepower, hence the Hurricane's relatively sluggish sales as compared to the Thunderbolt. FS followed the most economical path to success rather than tinkering too much with techniques that were hit & miss or just too costly back then, and they still provided a package that for the most part was universal throughout the offered range. Can you swap a 2001 rotor with that of a 508 and expect it to run smoothly? Nope.
PS: I want a Hemi option on the new blower.
