I’ve been playing for almost a year. The other day for some odd reason I bit down on the fipple. It seemed to help on fast pieces, especially those transitions that can make the whistle shake a bit. Obviously this would not be so comfortable on a metal fipple, and impossible on a Susato, but does anyone have a comment on the pros and cons of chowing down on the fipple?
Tom.
The only advantage I can think of is that you will be less likely to drop the whistle if you bite the mouthpiece.
On the downside, you’ll chew up the mouthpiece, and it couldn’t be good for your teeth.
The whistle is not a reed instrument like a clarinet or saxophone. Your embouchure will thus have little, if any, effect on the tone.
I think the steadiness of your airflow will have more effect on the tone.
Happy tunes,
Paulsdad
I tried playing while biting down on the fipple and it really destroys my playing. It restricts what I can do, and the tension is distracting. No fun. No fun at all.
YMMV
When I took up whistle, the closest instrument I had played was saxophone. I had to keep reminding myself not to bite. Reminding myself of the cost of the dental work on my upper front teeth usually did the trick but didn’t help much with musical inspiration. There are no benefits of biting I know of.
Biting is frowned on, as noted above it causes tension in the jaw and face, and tension is generally bad for music, especially the Irish sort.
You should be able to hold the fipple in your lips well enough, and don’t forget you can use 000 00X to hold the whistle steady when playing C#.
I would recommend you try to avoid developing the habit. It’s also a bit antisocial if borrowing a whistle.
There’s really no reason to put the mouthpiece far enough into your mouth to bite on it. Just enough to get a good air seal around the mouthpiece. Any more would inhibit tongue motion.
New motto:
Bite a Serpent, Lose a Tooth!
solid brass fipples, baby! 
Cheers,
Bill Whedon
The more loose I stay
The faster I can play
(I am a poet
And you did not know it!) 
–James
http://www.flutesite.com
Thanks guys. Whistling has brought me to realize that I’m a very tense person. I always knew it, but this confirms that I haven’t overcome it, even after 50 years of trying.
Grrrr!!! Argggg!!! GRAAHH!!