Spacing & sizing with libertine and newtxmath

I'm using the following setup for the Libertine font:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[lining]{libertine}
\usepackage[libertine, cmintegrals]{newtxmath}

\begin{document}

Test: $75 + 250\log_2 n = 75 + \frac{250}{\log_{10} 2} \log_{10} n$

\end{document}


But the spacing for inline math seems to be a little strange:

Compare the spacing of = and the numbers in the denominator to the output with mathpazo or mathdesign/Utopia:

In my opinion the Libertine results look more uneven and poorly spaced. Is this just how the font looks, or is there something I can do to make this look better?

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I agree that libertine looks suboptimal here (or is newtxmath to blame?). The "10" in the logarithms looks particularly bad, maybe the numbers are drawn from the wrong place (tabular figures). –  mafp Jan 25 '13 at 8:51
Check your log. I can't duplicate your output. –  user22108 Jan 25 '13 at 19:26
@user22108 Added MWE. It's very simplistic and exhibits the same spacing as my original screenshot. –  jtbandes Jan 25 '13 at 19:28
In my test, I added \huge; so it seems the small size is relevant. –  user22108 Jan 25 '13 at 19:34

The good news -- speaking specifically about the choice \usepackage[libertine, cmintegrals]{newtxmath} -- is that in the ca 18 months since the query was posted some corrections have occurred. If one runs the OP's MWE now, the output looks much better. This, of course, doesn't impinge on the validity of your observation that when it comes to fonts, "this is how it is" applies. –  Mico Aug 3 '14 at 11:39