MD3200/3220 SSD Cache

Hello -

I did quite a bit of searching, and the forum appears to be bone-dry in terms of info on the SSD Cache option for the MD3200 or 3220.  I have a hunch this is primarily due to "who" buys the MD3xxx series.  Meaning very price-sensitive buyers are less likely to double the price of their storage with SSD cache.

So does anyone who's tried this have some real-world numbers on performance gains?  My questions to the forum would are:

1. Real world performance gains from SSD cache
    
2. We are considering adding this to an existing MD3200 that currently has 48 spinning 15K disks used for SQL Data, Logs, and TempDB volumes.  Are there any limitations or recommendations on how to add the SSD drives when used as SSD cache to the MD3200?
    
3. There's very little data our there on the max IOps you can push through this device.  When testing with 64K IOs on sequential reads, it appears we're already nearly maxing out this device with as little as 12 15K spindles.  Does anyone have any real world data with what these controllers can handle in terms of max IOs and throughput against SSD and/or SSD cache?  With the numbers we're seeing, I'm concerned that as little at 4-6 SSDs could easily saturate the controllers in the 3200, but that's only speculation at this point.
   
   
4. I'm assuming adding the SSD cache feature is pointless unless you add the high-performance tier feature as well.  Any thoughts on that? 

Thanks,

- Jeff