I did ask Joseph Pohm for a quick check on his sample sets and it seems as if there will be a need for some very nice modifications of his comparison!
I'll do it very gladly. Here you have my first impression on Yalac v0.08 new feature, PreFilter. Preliminary results, only High mode tested, only compression ratio tested, there are no speed results here. I usually test Yalac on 4 sample set.
Set A - Primary Sample Set
Yalac v0.08 Preset High - PreFilter Off 57,69%
LPAC v1.40 ExtraHigh 57,32%
Monkey v4.01 High 57,31%
MP4ALS Garf -a -o32 57,25%
OptimFrog 4.520b Normal 57,04%
Yalac v0.08 Preset High - PreFilter On 56,46%
Improvement 2,10%, Yalac surpasses all four competitors.
Set B - BackUp Sample Set
Yalac v0.08 Preset High - PreFilter Off 54,69%
Monkey v4.01 High 54,00%
LPAC v1.40 ExtraHigh 53,94%
OptimFrog 4.520b Normal 53,73%
MP4ALS Garf -a -o32 53,54%
Yalac v0.08 Preset High - PreFilter On 52,78%
Improvement 3,49%, Yalac surpasses all four competitors.
Set C - Yalac-Unfriendly Sample Set
Yalac v0.08 Preset High - PreFilter Off 62,53%
OptimFrog 4.520b Normal 61,78%
Monkey v4.01 High 61,67%
LPAC v1.40 ExtraHigh 60,68%
MP4ALS Garf -a -o32 60,46%
Yalac v0.08 Preset High - PreFilter On 60,43%
Improvement 3,35%, Yalac surpasses all four competitors. I'll have to change Sample Set nickname...
Set D - Yalac-Friendly Sample Set
MP4ALS Garf -a -o32 64,40%
LPAC v1.40 ExtraHigh 64,32%
Monkey v4.01 High 63,99%
Yalac v0.08 Preset High - PreFilter Off 63,81%
OptimFrog 4.520b Normal 63,53%
Yalac v0.08 Preset High - PreFilter On 63,00%
Improvement 1,27%. With PreFilter Off Yalac is already better than three competitors out of four. With PreFilter On Yalac surpasses the fourth one as well, and gets very near to OptimFrog High (62,82%).
As a general rule, on all my four sample set, Yalac High compression ratio is now able to stand right between Monkey High and ExtraHigh, as well as between OptimFrog Normal and High. As Thomas pointed out, I can give a positive feedback (actually it's not really me, numbers speak for themselves).