The 1200 is a big improvement over 950 which was lacking next to 590. I have used a 1200 next to a 590 and it is a fair match. It ergonomics also become a factor too and you need to pick what you are comfortable with. For the money with either a 1200 and 590 you are not likely to be disappointed with performance.
Yes, the 1200 receiver is a big improvement over the 950. My ears tell me that, as did the QST review. The roofing filters are much more effective at the lower IF frequency of the 1200, and the DSP is better, also. The transmit audio features the same parametric EQ as the 950, while the EQ capability in the 590 is more rudimentary. I'm very happy with my 1200.
Hi, I sold a Kenwood sat440 and a Kenwood sat450 and bought a new 590sg. Love the rig like a shark loves blood. One small idea... I bought a quick guide that really helps navigate the controls. It cost about $20.00 more or less and it has really helped me in operating. Good luck, Jeff. KA8ZAW
You might also want to check out a few of the online help sites for both 590S and 590SG. I found these very helpful in setting up both transmit and receive audio. I particularly like a narrower audio filter for CW RX as I find this makes it sound a bit sweeter and easier on my ear. Mike