Keep in mind that over discharging the battery is very bad for its life but brief large current usages generally is not a problem. One caveat you want to keep the total Depth of Discharge (DoD) below 50% for best battery life (measured in discharge charge cycles).
I think it's important to consider the application in regards to cycle life.
A typical quality gel cell is good for many hundreds of cycles down to 50% DOD. In a portable amateur radio scenario you would be hard pressed to amass 500 or more cycles before the battery reaches end of life through time. I would take the "better to burn out than fade away" approach, running the thing to 80% DOD or even more if the equipment will still operate at the lower voltage. The idea is that if you're only running down to 50% you're carrying around twice as much battery as you need, only to throw away unused cycles at end of life. There is a tradeoff of life vs cost vs utility in any given portable scenario. Ah and weight may be more important factors than cycle life. It would be more practical to say, use a 7Ah gel and run it dead 100 times and replace it than to have to carry around a twice as heavy 12Ah gel and only discharge to 50%, if weight and portability is a concern.