I've used the Lalvain and have been pleased with the results. I got a free
packet from a King Arthur Flour class when they came to my town. I believe
they gave out the French sourdough. It has a lovely flavor and texture. You
do have to add supplemental yeast, from what I remember (I used it a couple
of years ago). I kept on using my own starter because I hated to pay for a
new packet ($6.95) every 12 loaves of bread, plus I liked the taste of my
own starter better. But I do think it's a great product and is worth trying.
Rosemary Finch