I have had the "Boot Option" screen problem come and go with my Sonnet Tempo Pro dual drive card ... it's working now, but I don't know what I did to enable that. Sonnet was able to reproduce the problem (I was on a MP 3,1 at the time, now on a 5,1).
The Solo x2 card does not achieve double throughput speeds if both SATA channels are operating at the same time (such as in RAID-0 with a single card) due to a single controller for both ports. This speed limitation "may" occur with virtual machines using the bootable Windows image (VMware or Parallels) since both OS X and Windows installations are being accessed through the 2 separate SSD interfaces. I haven't tried it... and don't know how you would measure it since it would only occur within the VM.
I have 2 of the Solo x2 cards and was never able to get them to work at the same time ... but I was also fighting controller conflicts with several different eSATA cards (including CalDigit eSATA/USB3.0). Once I removed the eSATA card and went totally USB 3.0 for external drives, I was able to get my current configuration working (MP 5,1):
-- OS X on Sonnet Tempo Pro with RAID-0 SSD
-- Windows 8.1 on Solo X2 SSD
-- Inatek 4-port USB 3.0 (new Mac version)
I am using the Orico PCI-E/USB 3.0 card and works really well
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