Luckily, so I don't have to do a lot of research and attribution, you aren't really disagreeing with my statement. You are just asking a question that goes beyond the parameters of my statement. I don't see that you have actually questioned whether less depth of discharge = more cycles.
I do understand what you are asking/saying. I talked about the same idea in a post to Alice in this thread http://www.robotreviews.com/chat/viewtopic.php?t=5859 However, there is a major difference between her situation and yours. In her case she was doing 2 runs with her Scooba, using about 85% of the battery mah and then doing a partial 3rd run, intentionally using the other 15%.
In your case you are, necessarily?, using 100%. I'm going to do a post to Gordon going into deeper detail about NIMH voltages and Roomba shutdown next, but my short answer to you would be, it depends. If the Roomba is directly in front of the home base when it reachs the voltage that triggers it to go home, it probably won't damage the battery very quickly. If it takes it a while to find home, or runs down to the shut off voltage without finding home, then IMHO it could damage your battery quickly, and could just kill it someday.
Whether the cycle difference is straight line is, I think, unknown, unknowable, and improbable. My (educated?) guess is that it is not. However, with any batteries, the battery chemistries are so affected by the impuritiesi n the components that little can be said for sure. That is the reason we'll never know how an individual Roomba battery will last in any given situation. I could have a battery that I do everything, supposedly, right, and you could have one that you mistreat in many ways, and yours might last longer. Batteries are like gambling. If you play by the odds, you will come out ahead in the long enough run if the odds are in your favor, but that has no effect on the short run. Thus Casinos make money in the long run, no matter what happens any given night.
All you can do is play the odds, and the odds aren't good on using cheap batteries (iRobot) down to deep discharges on a regular basis. However, if it is much handier for you to do the Max runs, and you don't mind replacing your battery every 10 mos. instead of 14 mos, have fun. I would probably do the Max runs. To me the convenience would be worth an extra $10 or $15 a year.
It would take me all the time between *this* Labor Day, and the *next* one to get the job done!