I've been a Sync Pro X user since version 1.0.1. Throughout that time, I've seen the application evolve from being the only OS X backup application to being the best one.

The feature set in Sync Pro X is what makes it a winner. One of those feature sets is the automation capability. For any given backup, sync, or bootable backup routine, you have a full range of start options and completion options. Among them are the ability to specify "Before syncing, open the file..." in the start options, and "Open the file..." in the completion options. Those features alone enable Sync Pro X to chain a series of backup functions to perform complex backup operations that would be very tedious to perform manually. For example, I can do a progressive backup of a server database (meaning, it will back up only the things that have changed since the last backup) to a .sparseimage file located on another computer on the same network. Sync Pro X fetches the .sparseimage file from the other computer, mounts it on the server desktop, runs the progressive backup, and then unmounts the .sparseimage file...automatically, at a predetermined time every night.

The possibilities with Sync Pro X are limitless. Because of the aforementioned file opening capability, it will run AppleScript files as start or completion options. Very handy!

The only gripe I have really isn't a problem with Sync Pro X at all. I would like to be able to make a bootable backup to a networked volume located on a remote computer. Unfortunately, due to a limitation imposed by the way OS X handles permissions on a remote computer, there is no backup application in existence that can perform that task. Data backup to a remote volume is no problem in Sync Pro X, mind you; it just shows up when you want to make a bootable backup.

And it's not just for networked volumes. Whatever drive you select as the destination drive for the bootable backup must be connected to the host on which you're running Sync Pro X via an interface that supports booting. That includes certain external hard drive controller interfaces. For example, if you have an external eSATA hard drive connected directly to your computer, you can make bootable backups to that drive using Sync Pro X only if the eSATA controller card supports booting. If it doesn't, you can sync to it or run a normal backup to it, but you can't make a bootable backup to it. Makes sense, because you wouldn't be able to boot from it anyway.

A few comments are in order here. If you're reading this review because you're looking for a serious, professional backup application, you've probably noticed the abundance of negative reviews and one-star ratings. That would give me pause if I didn't already know that Sync Pro X is solid, reliable, powerful backup application. I don't know what problems others have experienced, but I can tell you that Sync Pro X does precisely what it promises to do, and it does it consistently, reliably, and predictably.

With any application that provides as much power as Sync Pro X does, the user has a responsibility to understand how to use the software properly. Part of that is making certain that it's the right tool for the job in the first place. It really is the Rolls Royce of backup apps, but if you don't need the full range of features it provides, you'd probably be better off choosing one of Qdea's other backup applications.

Support is responsive and excellent. The developer has always replied to my support requests within 24 hours, usually less.

Finally, a word about the license terms. It is absolutely NOT true that the Sync Pro X license is good for only two years! I'm still running versions of Sync Pro X going back to v3.x on various computers. Once you buy a license a renewak, all versions covered under that license will continue to work (...well, as long as you run them with a compatible version of OS X). The software does not expire. Keep your installer .dmg files so you can reinstall your older versions if you need to for any reason. Qdea does not archive older versions of the software.