Justin, my post was a bit premature. I was just a little surprised at the (minor) increase in size over various compression levels, so posted without really thinking.
What I totaly forgot was that this was just one file.
To rectify I have just tested -5 on my "FLAC corpus" (28 files) and the results are a lot better.
Out of the 28 files 12 files suffer with the -v switch, but on the whole the compression improves from 59.843% to 59.754%, or 1,221,384 bytes in 1,371,283,088 (a 0.001% improvement).
As you can see from the figures, those that suffer from variable blocks (-v 1) are the files at the outer edges - generally those that compress the best (e.g.: Charlotte Church, Andrea Bocelli), but also two Motorhead tracks (-274 and -5,698). This variation reminds me of the window testing I was involved in for FLAC 1.1.2_CVS (1.1.3), with the two bounds acting differently than the core files... not sure if that's relevant.
When wisodev is kind enough to provide a compile of Rev. 42 I'll soon provide some more figures, using my Yalac corpus, including timings and using various "key" compression levels.
Wav Off On
Filesize Comp % Filesize Comp % Diff
====================================================================
44205884 30037774 67.950% 29996667 67.857% 41,107
40501484 18854486 46.553% 18860045 46.566% -5,559
41860940 32194824 76.909% 32179874 76.873% 14,950
36997004 11961940 32.332% 11965877 32.343% -3,937
41849180 22570842 53.934% 22499530 53.763% 71,312
43095740 31742309 73.655% 31646473 73.433% 95,836
98031404 52089827 53.136% 52103883 53.150% -14,056
29964524 22412071 74.795% 22412345 74.796% -274
44963228 18196142 40.469% 18207104 40.493% -10,962
37462700 25086008 66.963% 24958122 66.621% 127,886
35209484 24646149 69.999% 24626419 69.943% 19,730
39280796 26879523 68.429% 26836293 68.319% 43,230
35898620 24982661 69.592% 24917519 69.411% 65,142
44295260 30913592 69.790% 30808634 69.553% 104,958
.134433308 84608716 62.937% 84103316 62.561% 505,400
46214492 33193196 71.824% 33150151 71.731% 43,045
70752908 31462354 44.468% 31470864 44.480% -8,510
37989548 22986231 60.507% 22940337 60.386% 45,894
56989004 29822007 52.329% 29827193 52.339% -5,186
47973788 28413887 59.228% 28367289 59.131% 46,598
10974476 4525937 41.241% 4528149 41.261% -2,212
45400700 17135222 37.742% 17141711 37.756% -6,489
79469420 56785940 71.456% 56754994 71.417% 30,946
35719868 26702556 74.755% 26675013 74.678% 27,543
32309468 13942750 43.154% 13947729 43.169% -4,979
73810508 30283837 41.029% 30312140 41.068% -28,303
55389644 44922899 81.103% 44928597 81.114% -5,698
30239708 23258281 76.913% 23224309 76.801% 33,972
====================================================================
1371283088 820611961 59.843% 819390577 59.754% 1221384