[Avodah] Falling Tallis

[Moshe Y. Gluck]

>>Two questions: 1) I recall seeing R' Moshe Feinstein say that in the case
>>where the Tallis inadvertently fell, one does _not_ have to repeat the
>>Berachah if he was wearing a Tallis Katan - not like the Be'er Heitiv.
Does 
>>anyone remember such a thing, from RMF or someone else? (Yagati V'lo
>>Matzasi.) 2) I asked someone about this, and he said he recalled hearing
the
>>R' Yaakov Kamenetzky said that the current Minhag is not to repeat the 
>>Berachah should one's Tallis fall. Can anyone corroborate this?

      R' Neventzal shilt"a, in his sefer on the Mishna Brurah, says in the
name of RSZA to not say a new bracha. His reasoning is that 
the da''as of a person is that he will wear his tallis for all of davening
when he made the original brocha.

                             -- Mike

How does that reasoning trump the Mechaber and Ramah who clearly disagree
with it? Also, I'm not familiar with the Sefer you quote. What is it called?