oops... the problem was using a regular expresion to extract the keys, try 
use Sort::Key::Maker sort_num_str =>
    sub { int($_), $_ }, qw(int str);

[download]
this way I got... 
salva@cabo:/tmp$ perl /tmp/skm.pl 100
          Rate     GRT    sort S::K::M
GRT      945/s      --     -2%    -26%
sort     967/s      2%      --    -25%
S::K::M 1282/s     36%     33%      --
salva@cabo:/tmp$ perl /tmp/skm.pl 1000
          Rate    sort     GRT S::K::M
sort    61.0/s      --    -20%    -40%
GRT     75.8/s     24%      --    -25%
S::K::M  101/s     66%     34%      --
salva@cabo:/tmp$ perl /tmp/skm.pl 100000
        s/iter    sort     GRT S::K::M
sort      3.38      --    -43%    -49%
GRT       1.92     76%      --    -10%
S::K::M   1.73     96%     11%      --

[download]

update: benchmark results were wrong!

In reply to Re^4: Sorting Alphanumeric Arrays by salva
in thread Sorting Alphanumeric Arrays by slloyd

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