Sounds like the straight SSD build would have plenty of space for your needs.
I wouldn't worry about SSD longevity. They're designed to handle a LOT of written data, and reads aren't a problem for them. Even Intel's new 20nm NAND-driven 335 SSD
can handle a lot of writes, and the first batches of NAND on a new process node can be weak with the max number of writes.
I've attached a screenshot of some SMART/health readings from my own main SSD, which has been powered up pretty much 24/7 since I got it in March 2011. I've written over 5 TB to the drive and it's reporting zero issues. No retired blocks or program/erase cycle failures.