I'll give the other side of the argument....
I've tried the SC 3840 (old 3865) and the BD tuner. Both gave me very similar results. When running premium gas, I had plenty of power; however, in order for me to get 91+, I've got to drive 15 miles to get it. My closest gas stations only have 87 & 89 (both with ethanol). This somewhat forced me to use the 87 tune on both tuners. With the 87 tune, the truck felt better. It had firmer shifts and the transmission wouldn't upshift as quick, giving me a nicer acceleration.
So why did I get rid of them? For both tunes (91 & 87), I didn't see a remarkable change in fuel economy, which is what I purchased them for. Sure, there were weeks where I was seeing an extra 0.5-1.5 increase in MPG, but when measuring that against a year's worth of fuel economy logs, it fell within a standard deviation from the average. This made it impossible for me to determine if the change in MPGs was from the tuner, or from something else (better gas, air temp, humidity, lighter right foot, etc).
I don't race my truck and since the Hemi puts out gobs of power, an extra 10-25 hp wasn't beneficial to me...especially since it's at RPMs I don't spend a lot of time at. If you had a 4.7, this would be a no-brainer. The tuners (especially Superchips) work wonders on that motor. If you're looking to make your rig faster and you can't shake the "Moddin' Bug," then I'd say get the tuner. I'm an easy driver and don't need to accelerate like a rocket, so for my needs, a tuner isn't necessary.
Ultimately, ask yourself what you want to do to your rig. If it's your daily driver and you want to add the other bolt-ons (CAI, exhaust, and others) and you want to add HP/TQ (which you said you did), then maybe it's worth it to you. If you're looking to stay mostly stock, it may not be worth the $300-600 for a tuner.
Your results may vary.