I have never heard native Hebrew speakers confound NATA( with NAT(-AH, but I
admit that it may depend on the circles one moves in, or otherwise the bus
line one takes to work.
Israelis do not pronounce the shwa "na" because there is no such thing in
Hebrew. It is an oximoronic invention [aided by a terminological
misunderstanding of what the metaphoric NA( means?] for justifying the
E-E-E-ing of the language, and it appears to me that it is being purged now,
as a phonetic phenomenon, from the school teachings. Unfortunately they do
often stammer E-E-E out of place as a result of lack of education for crisp
speech.
They make no distinction between patah and qamets since there is no evidence
that these signs were introduced for phonetic distinction.
Isaac Fried, Boston University