I serously doubt that a single beep to indicate a preset level of puffs (or whatever) would use a MUCH power as that damned LED on the tip of most batteries, which turns on whenever the power is applied and stays on until it is cut.

While neither consumes a great deal of power, the LED spends MUCH more of its time powered up.
LinkReincarnate: I could be wrong, but I think most of the people who tossed ideas into the hat were more or less doing thought experiments and enjoying discussing whatever possibilities could exist. But, I've been wrong before. As for myself, I'd probably get a kick out of the info provided by the LCD 'suggestion' I threw in. But, in my view, that feature would just add to the geekiness of the device. And that appeals to me. As far as adding clunkiness by the addition of a beep, a tiny peizoelectric transducer and a tiny chip to control it would probably fit inside most PVs without any kind of physical outward change, other than a tiny port for the sound.
Now, a USB port for downloading saved statistics would necessarily add "clunkiness", but wouldn't it be kewl to view and graph the data on your PC?
Not that I think any of this stuff is likely to be offered ... nothin' wrong with conversation, huh?