2012 27-inch iMac 768 Flash + External Storage vs. 3TB fusion + External Storage

The objective is simple, I want my Aperture library to be snappy, responsive, fast imports, exports, adjustments, etc.  You guys get the point.  Got spoiled running Aperture off an SSD.

If I order the 768 Flash drive, I will then have to install an external USB device for extra storage (music library) which I already have.  I will have a total of 1.7TB - exactly what I have today in my Mini.  The .7 will be on the flash and I can run my Aperture library there with not so much room for growth, and my music and what not on the external USB3 enclosure.  No doubt I will have to upgrade the disks in my external USB3 case from OWC.  Maybe 2 WD Black 2TB.  My library will be super fast, but not a lot of room to grow it..maybe 100GB, scary.

Other choice is the 3TB fusion (don't care about boot camp), and still have my 1TB external USB.  A lot less money spent, and I have 4TB of storage space.  Aperture library will have plenty of room to grow and I will have more money in my pocket.

The question is how will Aperture run on the Fusion drive?  Does anyone have any experience yet with this?  Apple says imports will be faster, etc...but wondering how daily use it like

And if it's not snappy, then would any of you recommend a good external solution for an Aperture library?  I have read up on LaCie, Pegasus, Seagate, and so many others and it's like one 80% solution after another.

Would love a simple external 512GB SSD Thunderbolt storage solution (avg 300 r/w speeds)..but seems that most 2.5 TB enclosures don't work past 256GB due to power problems.  There are plenty of USB3, and maybe thats the right way to go, but have read about USB 3 disconnects and that can't be good for a DB!

Open the floor to discussion