Is using the SysRQ Emergency Remount an acceptable way to clone hard disk?

I'm using Linux (Ubuntu) and I was told that I can use the method described below to clone the system's hard drive to another one - to plug into a new machine. (Without booting from a Live CD) It assumes that the system's disk is /dev/sda, the partition mounted as root is /dev/sda1, and an empty disk to clone it to is /dev/sdb.

u > /proc/sysrq-trigger

Remounts all filesystems including the one mounted as root read-only.

-fy /dev/sda1

Corrects the filesystem errors caused by forcing the R/O remount.

if=/dev/sda of=/dev/sdb

clones the disk to the empty one.

-fy /dev/sdb1

fixes the newly cloned filesystem. At this step it usually tells about fixed block checksums.

-f

Reboots the system. At this step I disconnect the newly cloned disk, and plug it into a new PC. I've used this method two times, and all machines are working fine, but I'm afraid that doing that could cause some dangerous filesystem issues? If yes, why? And should I avoid using this method to clone hard disks in the future?