I think with Sandisk - you're paying for name recognition and not necessarily reputation. If you look at their user reviews, they have as many problems as most other brands. Specific to miniSD - I noticed that the Sandisk cards were much slower than the competition for the same price level.

When purchasing miniSD cards, I'd recommend balancing performance (speed) vs. Reputation/Reviews. Though that'll only matter when using the card in another device - I don't think the 6700 can take advantage of the higher speed cards.