OK I'm gona be honest with ya from my experiences form the past 3 weeks with a tuned ECM and a SCT with the same tune from a different supplier. I;ll call both " other" to not name companies.
I started off with a Stage 2 tunes ECM and it was night and day difference!
The main thing IMO it does is allow you to climb in RPMS past the 5250 stock setting to 6000RPM where those last R's really shine. I also raises the shift points and firmness some to match the extended RPMs. They also bump the timing a lil to wake her up.
I then received an SCT with another vendors tunes and it was EXACTLY the same ( although I cannot look into the ECM parameters to verify) as the tuned ECM. SAme RPMs, shift points and almost forgot the earlier fan settings. Torque management on both tuners is removed and wakes a QC up dramatically.