Not really. A character needs to grow. How sad would it be for Eric to turn into a 40 year old fratboy manwhore? Yes, there are 40 year old fratboy manwhores, but they're very immature and crass and just plain disgusting, and Eric is not like that.
Some characters shouldn't change (House, Grissom) because the essence of their shows depend on that. But others need to, and I think Eric falls into that category. Calleigh, not so much, she just needs to let go of some of her inhibitions, but I think from the get go Eric was set up as the journey man. Losing your best friend then sister, then getting shot, is a big deal, so I don't expect him to ever be the same guy he was. No one would. I think it's realistic and luckily they've handled it somewhat well so far.