Are there any major advantages that LTE has over HSPA+ besides speed? If not, and I were ATT then I would be inclined to focus on deploying an HSPA+ network that can match Verizon in coverage. Beat them at their own game. In the long run, nobody is going to care if you're getting 42 mbps down vs. 60 mpbs. We are years away from having modern day internet utilize all that on mobile devices.
Well an advantage of LTE is that it is deployed in clean unused spectrum which can take some of the data congestion from the HSPA network.
Other than that, at this point in time there isn't any advantage other than speed. This is primarily because LTE is really new and they don't even have voice running over it yet. A disadvantage is that it will more than likely consume more energy.
Until LTE is fully rolled out and voice is working over it so that we are just primarily using LTE on our phones for everything, I am more inclined to stick with HSPA.
If i get real hungry for data while out and about, then I may consider getting something LTE capable, but that isn't the case right now for me.