glad it might help..
anyone today would probably find Windows 8 sans Metro to be fine.
and most people today do use SSD for system, and use other drives for data, scratch etc
the limitation of not having more pcie aux power cables and connectors limits things too much. an 8-pin would have made life easier to have two GPUs
Between cloning - I use Paragon on Windows, acts somewhat like Carbon Copy Cloner insofar as making a bootable backup I can plug and go - and backups - TimeMachine or FileHistory
Some have managed to 8se the default ATI 5770 for GT120 for boot screen and still use the GTX 570 and above.
A PC at least you can SLI - and there are some people around here, ex-USAF, that really get into X-Plane and more.
Ability to use a gpu with more than 2GB is very recent and has been glass ceiling for years. Now people are seeking out 2.5 to 4GB cards to use. And what I expect has to happen soon is a motherboard with PCIe 3.x of course, better bandwith and power management... and SATA3 for your SSD does make a difference.
If you look at Sonnet 6G PCIe 2xSSD setup is bootable and put your system on steroids - don't know if it makes flying smoother but might. A couple Samsung 840 240s.