Thanks Trav, interesting. If mothers are motivated to breastfeed (whatever that may mean precisely) then it doesn't seem to affect duration of breastfeeding up to 3-4 months (which is as far as the study went). I think it's worth noting that that larger study they are drawing on here recruited mothers at the 2-week mark.

Implications for practice
In motivated mothers, there is moderate evidence that pacifier use
in healthy term breastfeeding infants before and after lactation is
established does not reduce the duration of breastfeeding up to four
months of age. However, there is insufficient information on the
potential harms of pacifiers on infants and mothers. In the light of
the current review we recommend that until further information
becomes available on the effects of pacifiers on the infant, mothers
who are well motivated to breastfeed be enabled to make a decision
on the use of a pacifier based on personal preference.
Implications for research
Further research is recommended to address the effect of paci-
fier use on duration of breastfeeding that include less motivated
women. We also recommend well-designed RCTs to assess the rate
breastfeeding difficulties faced by mothers associated with pacifier
use and the long-term effect of pacifier use on mother and infant
health.
Ryatha, I strongly suggest you get it treated regardless. A lot of babies with (even minor) tongue tie end up exhibiting symptoms of reflux and get treated for that, when it's actually the TT. Not worth even a small amount of pain really.
NEither of mine were ever keen on dummies either