Comment 6 for bug 1169488

The bit in question seems innocuous enough:

if ! dpkg -l | grep -q obexftp; then
    echo "You must install obexftp to run this script"
    exit 1

Would it make a difference if run in a subshell like this:

if ( ! dpkg -l | grep -q obexftp ); then
    echo "You must install obexftp to run this script"
    exit 1

or better yet, is there a better way to determine if a package is installed?