They have been reliable for me, I've run at least one pair for 4 years formatting them hundreds of times.
Speed is the issue. The newest set I have doesn't seem to break 260 mb/s while the older set has settled at about 330 mb/s write speeds.
You would have to test out what frame rates and compression you would use in your camera knowing it's not on the approved list.
While the price has stayed under $200 for a few years for the 256gb card though I think the Angelbird 1TB is now the best dollar per gig value at $650 at B&H.