I have never been able to develop film without scratching unless I use a hardening fixer. I took the recommendation of someone in this forum to try non-hardening and the first sheets I developed had scratches. Not his fault - I am the clumsy oaf. I do try to be careful, but I have learned that a hardening fixer is the insurance that I need.
There's an extremely important implicit point in your post: You're using sheet film. You don't say how you're developing it (in a tank, a tray, a drum, etc.), but the processing method can be extremely important in determining whether you'll get scratches or other types of damage, and the processing method is likely to vary from one film format to another. For roll films, processing is usually done in a tank on a spiral reel, and the risk of scratching during processing with this sort of setup is pretty slim, in my experience -- at least if the whole process really is done on the reels. (Scratches might occur if the film end curls up on itself after processing or if you take the film off the reels for a dunk in wetting agent at the end.)
Also, note that a hardening fixer will only help prevent scratches that occur during or after the fixing stage. If something is causing scratches during processing (vs. shortly after processing), that something could affect the film during the development or stop bath steps. I've heard of separate hardening baths that can come earlier than the fixer step, but I don't recall the details.
I don't think that there is any downside to using a hardening fixer, so why not use one?
There are downsides:
- Hardening fixers require longer washing times or use of hypo clearing agents to achieve short wash times. This increases costs and/or the environmental impact of processing.
- Most (or all?) hardening agents in fixers require acid fixers. Some people prefer neutral or alkaline fixers, for a variety of reasons, so using a hardener limits your choices in this respect.
In short, there
are drawbacks to using a hardening fixer. My personal preference is to use non-hardening fixers (TF-3 lately) -- but I also shoot 35mm and MF exclusively and process in tanks with spiral reels, so I'm not concerned with processing issues that are unique to sheet films.