After several thousands of mile and over 40+ years of two wheeled travel, I have come to understand the need of both types of panniers...hard and soft.
Hard panniers, metals, cans, soups, tins, or whatever else they might be called have a place and a risk in any type of GS riding. The most argued point I see is for them is security, I like it, but I feel its not necessary. Traveling internationally and in some pretty cagey countries such as the Soviet Union in the mid 1990's, I never travel with stuff I am not willing to loose! So, the security factor, for me, is mute. However, keeping things protect from impact, as a frame of the word security, makes sense. Ideally, I wear a small day pack by Arc-Teryx, its padded, holds my precious laptop, Go-Pro, and other valuables...on heavy tours, I supplement space needs by using my Toura Tech tank bag which quick releases. Another argument for using "Tins" is that most designs have built on tie-downs for adding gear to the lids. On most multi-day tours I put my tent on one side and balance the weight on the other with an air mattress *sissy here! The ability to add on extra gear, balance it, secure it from shifting is an asset not available on most soft bags. To place this into context, I can and have hauled about 125lbs of camping gear with a passenger for over 3K mile tours...on my F650GS (2012).
Softies, Bags, Gravel-Pillows, or Sacks, have their place in my collection of GS gear. The most profitable reason for hauling soft bags is they cushion the bike in a reasonable drop. If you are really crafty, have some fast clip fasteners installed so when you do go down and you know you will, they pop off and save tearing straps etc. Consequently, the knowing this, I use soft bags when I am out GS Adventuring on mostly dirt or harder roads which I know pose a higher risk. Softies are cheaper to replace, tend to stand up to more abuse, and when they get that nice road-rash petina, they stimulate some story telling...unlike when Cans are crashed, cans deform and at the best outcome, will leak from then forward. I love my Wolfman softies when I am raging along the outback. As for security, I have had one of my Cans pried open in an attempt to get the locks to pop. It ruined the can and left me with wet gear for the remainder of the tour, and it rained allot! When I have soft bags, I tend to take them with me more, using them like small suitcases...when I have my Cans on, I tend to leave them on the bike...my trust in the analogy that metal was a safer...proved not so!
Back to the beginning, never take what you are not willing to loose, make a educated guess regarding the type of riding and the demographics before you decide on which type of panniers to use. If you can only afford one type of pannier, my suggestion is to go for Cans due to their universal use...just pray you don't take a hard digger on them!