Do you still think that these days it is as essential as it was to give an SSD 6 months out in the wild before buying it? I think SSDs have matured beyond all recognition beyond their predecessors and aslong as it was purchase from one of the major reputable vendors I would not hesitate to buy a new drive.
Incidentally Samsung's track record is probably the best in the industry. AT said that Samsung's early drives were slow but rock solid unlike pretty much everything else out at that time. The 470 was slow, but solid and the 830 has been fast and solid. Considering their reputation, tight OEM integration and with the 840 being an evolution of the 830, I'd be very suprised if this drive had issues.
Lehtv answered this before I could, but I would like to add a few things:
1) Intel, not Samsung, had the best rep, in many circles.
2) Samsung SSDs have had major glitches, believe it or not. See, e.g.,
http://www.anandtech.com/show/5460/samsung-updates-the-firmware-of-ssd-830-series-fixes-bsod-issue
Intel is not immune, either; they had a 8MB glitch for instance. Crucial (more accurately Marvell?) had the 5200 hour bug in the M4.
EVERY company is capable of messing up. No matter how much you want to pump up Samsung's rep, coding is done by humans, and humans can make errors.
3) The price thing is the other reason why I would go for the cheaper, older, proven SSDs. What does one hope to gain with a 840 Pro? I can't even tell the difference between my X25-M G2, M4, and 830 drives outside of very large sequential file transfers.