Are there any special implications of Write-Back vs Write-Through that should be considered when creating an SSD raid array?
I'd say that write-through would be a better solution, as you don't suffer from the problem of waiting for the data with low access times of SSDs.
That being said, I'd still measure how both setups perform.
The second thing to watch out for is the bottleneck in the controller: hardly no hardware controller can do sustained 800MiB/s+ read/write to the array. You will need to leave quite a few empty SAS lines to not leave the SSDs underutilised.