I have used Instruments.app for my programming and I've used Valgrind, and there have already been two cases that dtrace (the provider that Instruments uses) ha

I have used Instruments.app for my programming and I've used Valgrind, and there have already been two cases that dtrace (the provider that Instruments uses) has found memory leaks in my programs that Valgrind did not complain about, nor care about. As for tracing system calls, dtrace is extremely powerful, and I much prefer it over strace where I a lot of times get a lot of garbage and have a hard time slimming down the output. I bet it comes down to what you are used to, and this guy is used to his Linux developer tools, whereas someone like myself would feel lost without dtrace, ktrace (trace on Mac OS X), sample, and various other tools that I use on a regular basis.