We bought two identical 50 watt leads over a year ago, both with MV.  It really gave us the chance to do a lot of comparing.  The first change I made to one of the heads was to get rid of the Mallory 150 caps and install the "basic model" Sozo's.  With just that change alone, yes you could hear and feel a difference between the two heads.  We had quite a few players (I believe it was 5 guitarists)  test drive the heads for us side by side.  Nobody was told which head had the Sozo caps installed.  We just told the guys that we had made a change to one of the heads.  Four of the Five players said they preferred the head with the Sozo caps.  Nobody said either head sounded "bad", just that they definitely preferred one over the other for tone and feel.  Because I knew which head had the Sozo's, my opinion is biased, but I preferred the head with the Mallory caps. 
So that is my experience.  If I had to make a definitive statement I would say, "You will hear and feel a picking difference with a change to Sozo caps, but it is impossible to say if you will think the Sozo sound is "better" or not". 

To prove or disprove that, we would have had to buy two sets of caps at the same time and assume they were all made from the same run of materials.  Then you would have to put 100 hours on the one set of caps, then install both sets into our two similar amps.  That is something we did not do, so I really can not give an opinion.  I have a hard time accepting a "break in" period for caps, but I am sure there are knowledgeable people that will defend the theory.  Personally speaking, capacitor break in time is something I will never worry about.
Good Luck

Yes the sozo caps dont change the tone a lot but they change and improve the dynamics and pick attack.

Like I said in my first post, we bought the "basic" Sozo's.  That is to say, the least expensive caps they make.  Not even sure if they had the "Vintage" caps then.  My gut feeling is that it is not worth the money to buy coupling caps that cost as much as the Sozo Vintage, or even more expensive.  Of course to back up my statement, I would have to do a similar test with the "Regular" vs. "Vintage" caps. 
I really believe that Mallory and Orange Drop caps are very good  and toneful enough for anybody.  There does seem to be a lot of builders who use Sozo in their amps.  (I believe Doug Roccaforte is one of them.  And I have nothing but respect and admiration for that guy).  Don't know if the builders use Sozo as a selling point or if they really hear a difference themselves.  I think the "Basic"  Sozo are 2-3 times the price of Mallory 150.  For most people I think they are probably worth a few extra dollars.  Who knows, it all kind of gives me a head ache after awhile.