Let me clarify this issue once and for all. Officially you use 10th edition. Neither 9th, nor 8th, etc.
Content however is only marginally different. Main issue here is home assignments. Usually publishers when preparing new edition shuffle problems like card sharpers to discourage of usage of the old edition because they want bigger sales. In this case there are some discrepancies, not very significant. Therefore using older edition you can add up with solving the wrong problem.
However you do not submit home assignments, they are not graded at all, but you are given quizzes drawn from the problems in the home assignments. So if you solved the right problem, you would solve during the quiz exactly same problem. If you solved the wrong problem, you would solve during the quiz similar problem, which makes a difference.
Yes, we posted online required problems for sections 1.1-2.2, but it was done only because textbook has not arrived to bookstore yet, so we were dealing with a problem of not our making. However it is time consuming. Creation of comparison table is also time consuming and error prone. So, you should not expect instructors to be involved in this. if there are volunteers--go ahead! (IMHO, if there are two independent pairs it would be more reliable).
PS. I have no idea how much the textbooks authors profit. AFAIK none of them is on the Forbes list.