Chuck wrote:

> And if you each had a specific mouthpiece like I have on mine, there is no
> possibility of a mistake since your mouthpiece wont fit her and hers wont
> fit you.

Everything is a trade off.  The choice to use a custom mouthpiece triggers a
number of other issues, some of which may be important to some divers:
1. It tends to dictate which second stage is donated in an emergency.  A
custom mouthpiece is less suitable for sharing than a standard one.
2. The choice to donate the alternate rather than the primary negates the
benefits of breathing the long hose and any advantages that led to the
choice to do so in the first place.
3. The choice to donate the alternate pretty much elminates the option of
using a combination alternate/bc inflator.  In my opinion, this is the
primary reason that donating the primary is becoming the more common choice.
I think DIR is the second most significant reason and that expecting a diver
to grab the primary is largely a post decision rationalization.  I could be
wrong.
4. A diver with a custom mouthpiece, or any other equipment that forces
choices that depart from the mainstream surrenders any advantages they may
have gotten from equipment standardization.  The DIR concept may be a bit
much for an entire recreational industry, but it's hard to argue against the
advantages of a common configuration and common use.

This is a kind of long post for something as simple as a planned change in
mouthpiece, but these are all things I considered when setting up my own
equipment.  There's nothing conclusive in all of this, just things to
consider.  In my case, the final choice was dictated by even more basic
issues.  I have such a strong gag reflex that anything larger than the least
intrusive mouthpiece available is undesirable.  I suspect that the nature of
the event would let me overcome this if I had to use Chuck's primary to get
safely to the surface.  On the other hand, being out of air, mentally
stressed and vometing isn't the kind of contingency plan I favor.  YMMV.

Lee