I recently posted a question regarding the differences between the Deore and Alivio. The responses were that the Deore is better or on-par. RD and FD should be reliable and durable on all of the models but I think on this board people will tell you to lean towards the 7.4. The fork on the 7.4 is a carbon fork. Between the 7.2 and 7.3 - I think the 7.3 is the better choice.