Becky,
Certainly poor weight gain is something I see a lot of with bubble palates.  I
think I mentioned this previously but it's worth another mention.  When the
baby pulls the nipple into the concaviety(bubble) then often the areola does
not get enough stimulation to produce a good milk supply.  This then leads to
the poor weight gain.  I am not sure if what I'm feeling is really such a weak
suck or if it is just that the suck feels weaker when the baby doesn't take the
finger back far enough.  What usually happens here is when I work on correcting
the latch-on, positioning and teaching the baby to take the nipple back to the
juncture of the hard and soft palate, the suck and milk supply improves.  Then,
of course the weight starts to pick up.
Yaffa Stark, MA, IBCLC