I took my nephew out this past weekend, and, as part of his lesson, we used our sparklights and natural tinder. the tinder has to be VERY dry, and, if you mold it into a sort of nest, and aim the spark into the middle of it, it works ok. But, it did take about 15-20 mins for it to catch a spark. Using the provided tinder-quicks, it caught immediately. All were we doing was catching a spark & getting a flame going; not building an actual fire. Not as easy as it seems!
I also tried with my gerber tinder thingy; I gave up soon enough. Took too damned long <img src="/images/graemlins/wink.gif" alt="" />