It looks like in OS X 10.11 El Capitan, dtruss and dtrace can no longer do what they're meant to do. This is the error I get when I try to run sudo dtruss curl ...:
dtrace: failed to execute curl: dtrace cannot control executables signed with restricted entitlements
I've come across people noticing this problem but so far no solutions.
Is there a way to fix this or work around this?