I'd say the 7.2 is well worth the extra money. What you run into as you move up the FX line is "maintainability" Can a component be greased, adjusted or repaired versus replaced. For someone riding 100 miles a year this isn't a big concern. If you ride 5000 miles a year this is a big question. I have a Trek 7300 which is somewhat similar to the 7.2 FX after 2500 miles the rear derailleur was tired. The Alivio derailleurs are riveted together and there isn't anyway to fix them. I upgraded to a Deore LX which can be disassembled, greased and some replacement parts can be acquired.
It can be really tough to decide where to stop in the upgrade process especially when it's that second bike.
P.S. providing a link to a bike you have a question about makes it easier for others to comment.