Handheld Tuners vs. Nelson Tune

I have some questions about different tuners. I've got a 2005 2500HD with the 6.0 and 4.10's. It has decent power, nothing great, but it gets me by for what I need it for which is pulling a 24' stock trailer once in a while. I've tried to read up on posts about the Nelson tune, but I'm a little hesistant about it because of some of the problems that could occur after installation. I'm too far from him to do a dyno tune so I'd have to get the mail order. Most of the posts I've read about the handheld tuners like the Superchips say that they are a waste of money. However, I've visited with people who have used the handheld tuners and thought they really helped out. I'd like to know some honest opinions on people who have used the Superchips, Hypertech, etc. tuners and see if they are worth the money. I'm not expecting mind-blowing gains, just a little more pep to it. Also, is there anyway to increase the mileage with a tune? I know it won't get great driving around the farm, but 12-13 on the highway just plain sucks.

i installed a hypertech 3 on an H2 and the difference was noticeable. its more responsive and shifts better. i think people expect alot more from them, but a handheld tuner that is applicable to all 2500hd's w/ a 6.0L is going to be modest. so depends on what your looking for. the handheld tuners you can get for $300 and do it yourself=very easy(install/uninstall whenever you want), if someone gets in there w/ a laptop-your stuck with that unless you take it back to them and its probably closer to $500 if its a decent tuner w/ a dyno. as usual you get what you pay for.