I've not seen these adapters but I can think of a couple of points anyway.
Pros:
CF cards are prone to bending pins on the connectors. Leaving an adapter in place could end up saving big time. I know of two people who've ended up getting new cameras after bending a pin on the CF mount in their DSLR.
These days CF is not as universal as SD. Many or even most tablets/laptops/viewers... will take SD cards very few now support CF.
On the cons:
I suspect an adapter & top SD card might not be as quick as a top CF card, but it will certainly depend on the actual card. The adapter itself may introduce read write delays too.