Nice...
Not really.
Don't be fooled by the OWCs benchmarks and read/write data.
Swapping out the Samsung 830 for a sandforce controlled OWC SSD is a "downgrade" overall (except more capacity).
Not worth it.
You void your warranty for a SSD that is a poor performer.
If you really need more storage then you're better off getting an external drive via USB 3.0 on the 13inch rMBP.
A 256 Samsung 830 which can be purchased for around $200 housed in a USB 3.0 external enclosure would be better for more capacity than swapping out a good ssd for a poor performer like the OWC ones.