While I have no experience with the Icom products, I have had both the TS-590S and the later TS-590SG over the past 11 years. When I see others panning the Kenwood's DSP noise reduction, I never see them refer to the fact that the Kenwood actually has two different noise reduction systems, strangely dubbed NR1 and NR2. (Kind of sounds like Dr. Spock. . . Thing 1 and Thing 2?) Bear in mind that I live in a residential city environment, with a ground-mounted vertical, so my station is probably a noise-magnet.
I have noted that the NR systems on the 590SG seem to be a bit more advanced than the similarly named tools on the 590S. I also note that NR1 and NR2 are vastly different. NR1 never gives any "under-water" effect, while NR2 does when it is set anywhere above 5 of 10. That, to me, is fact. I have no problem with it, though.
Most of the time I only need to use NR1, set to level 8, 9, or 10. I do not note any warble artifacts with NR1 at all, and the noise reduction is VERY effective. If noise is really bad at the time, I do sometimes use NR2, set to 7 or 8. Some loss of audio level on SSB, but still intelligible. With NR2 on CW, the situation is the opposite. There doesn't seem to be any warble, but the attack time at the start of each dit or dah seems sharper, making it easier to discern characters in high noise situations.
I agree that the perceived quality of the noise reduction tools on modern rigs depends upon what you expect from them. I do not agree, though, that somebody else's experience can adequately tell me how something will work for me. I really think that the 590SG is an excellent rig, near bullet-proof, and with excellent ergonomics. True, it lacks the eye-candy of the newer rigs with band scopes and all, but when you've grown up (nearly 60 years as a ham) without having to run your rig from a computer screen, the straight-forward user controls of the Kenwood feel mighty good.