This is absolutely fantastic! The only thing I would change is the ability to suppress logfiles and have the program clean up after itself (i.e., removing the siqs.dat file and other files when it finishes).
Excellent program, the best in its class by far. The developer is very hard working and dedicated to making this a great program. I have had very quick turnaround times on bug reports and feature requests.
AFAIK YAFU has the world's best QS implementation, and its ability to intelligently choose a factorization strategy on its own is really marvelously useful. YAFU is pretty much where it's at for integer factorization.
An excellent factoring utility by a dedicated developer.