I'm looking to replace my old MOTU 24io and I'm leaning towards the Studio Capture.  This is going into a new Intel i7 Win10-64 build so it will probably be on this OS for many years, I'm only now leaving Win7-64.  It's main competition is the Tascam 20x20.  Here are a a couple of questions:
Are there any drawbacks to USB 2.0 (Studio Capture) vs USB 3.0 (20x20)?
Any experience with it under Win10-64 with Sonar Platinum (most current version)?
 
It looks like they are both well liked but the Capture is kinda old so not too many current reviews around here.  It's age seems to be it's main drawback but maybe also it's a mature product now.  I do worry about driver support for it after another 2-3 years in case a major Win10 update happens that it won't run under.
 
As far as IO the Capture is perfect for my needs.  With the 20x20 I would need to buy an additional 8 channel mic pre/converter.  I like that the Capture can do 4 separate monitor mixes.  If I understand correctly the 20x20 can only do one.  In my 24io I make up to 4 to send to my SM ProAudio HP6 (headphone amp).  It has 4 stereo inputs and 6 headphone outs and each out selects from one of the 4 mixes.
 
Thanks for any advice on this.
 

I used to have both a Studio Capture and an Octa-Capture.  They are both gone, primarily because of Roland support.  The Studio-Capture I just didn't like although its basically the Octa-Capture with more inputs (I bought the Studio Capture as I thought I would need more than 8 inputs but never did).  The Octa-Capture developed a problem with the headphone output.  Being a former amp tech I replaced the headphone jack as that appeared to be the problem.  The headphone jack didn't fix it and I talked to Roland about a replacement headphone output jack board (a small separate PC board).  I was told I would have to buy a package containing the main board and the headphone board as it wasn't sold separately for almost $300 (plus it would have to be ordered from Japan).  The Octa-Capture was sold to someone that didn't need the headphone jack.  
 
Roland was slow to get Win 10 drivers.  The Win 10 Beta's had been out over a year (giving vendors time to develop Win 10 drivers) but Roland didn't bother.  The drivers they had for other OS' (such as Win 8.1 or Win 7) were written for the specific OS so they wouldn't install in Win 10.  We were left out for several weeks after Win 10 was released.  (I had a Roland/Edirol PCR500 keyboard and it was never supported for Win 10). 
 
Sorry about the rant on Roland.
 
As far as USB 2.0/3.0, according to our resident guru we haven't reached the full capacity of USB 2.0 so USB 3.0 isn't really needed.