Like Russ, I bought the
WINTEC FileMate 16GB Professional Class 10 card based on good reviews. Rated at 10 MB/sec or better for read & write -- that's the basic Class 10 definition.
I also have the
SanDisk Extreme Pro 16GB UHS Speed Class 1 card. Of course the K-5 can't use UHS speed. This card is rated at 45 MB/sec for read & write (300x).
Both have a Limited Lifetime Warranty, although SanDisk says it's a 30 year warranty in Germany.
But for those of you who remember floppy drives, their "Lifetime Warranty" was for the lifetime of the product -- not the buyer's lifetime.
With new empty cards
I ran a simple speed test on both: filled up the K-5 buffer with continuous RAW images, then clocked the complete write cycle. The results were identical.
So it's clear to me the camera can't take advantage of the more expensive SanDisk Extreme Pro card when flushing the buffer. I didn't test image playback. Not too concerned with read speeds.
But not all Class 10 cards are created equal -- Class 10 only specifies a minimum speed for read & write operations. I plan to buy a cheaper Class 10 card in a couple weeks to compare.
SanDisk does say it has increased endurance through wear leveling. Wear leveling is important since flash devices can only write/delete memory blocks so many times before they are unable to store new data. I understand reading doesn't contribute to wear and you can read data from flash devices even when it won't accept new data.
I'll leave it to someone else to test wear leveling on these cards.