Are you makpid on Shva Na ?

There are places where proper pronounciation is important as we discussed before in another OP. It changes the meaning. ידמו כאבן. Having a dagesh chazek in the the dalet makes it yidumu meaning silent whereas yidmu means similar or like.

Yes, I try to be extremely makpid. Boruch Hashem for Artscroll — they designate the havarah and shva’s clearly.

“just recall in your mind the first time you heard Avinu Mal’kenu as Oooviniii Malkiinii etc”

I assume you mean “avini malkeini” as in Chassidishe havara?
Nobody says malkini.
Either way, nothing you said is anything close to Litvishe havara.

To the best of my ability, yes.

I don’t necessarily get it right every time, but I try my best to pronounce a Sh’va Na/Nach correctly, especially since it sometimes changes the meaning of the word.

The Wolf

Perhaps more important than over-stressing vocalization of the na, is understanding that a na begins a syllable, whereas a nach ends one. There should be some vocalization in any case, as in distinguishing between, e.g., Vayyir-u (“They saw”) and Vayyee-r’u (“They feared”). Keep in mind that some cases of sh’va are subject to machlokes. Much of dikduk taught in America is by the German community (who fortunately do place some emphasis on dikduk in chinukh, realizing its importance), many of whom pronounce as na` a sh’va m’rachef (e.g., בגדל זרועך ) – and this also includes a m’lap[f]um ganuv (a sh’va after a shuruk which some might say could have once been pronounced by some as a vocalized semivowel) – and other sh’va-im (e.g., ועבדתם, ואבדתם ) – sometimes for tiferes hak’ria purposes. I’m not faulting those who hold this way, however we must realize that this is certainly not always l’khol hadai-os, even though at times when taught or presented, it can give that impression. Many grammarians (and I don’t limit this to ‘maskilim’ or ‘modern’ grammarians – it could easily include those such as the Gaon [G’ra] and the Rada”k in many cases) would often hold otherwise.