Steve: 

I wasn't a where that that's how the 590's capability was, that's pretty cool and convenient. 
The older rigs more or less saw what was connected to its antenna jack, either an amp or manual ATU and of course, the older KW's with voice didn't announce SWR. 
I think the older KWs though displayed the SWR of the antenna tuner if it was 1 of the radio controlled models, with its internal ATU by passed. 
Pretty gd if your were running a 5 or 600W solid state amp? All you'd have to do is set things up with the ALC and just flick the switches and go. LOL No talking meter really required if you were adventurous and didn't want a net. LOL 
Hook up the amp by pass on the 998, press the tune button on the 590, the amp goes into standby, rig transmits a 10W CW to activate the 998. It tunes and then the amp comes back on line. The ALC has the drive controlled to about 60 or 75W and the amp is kept down to safe power levels. LOL 
I got to admit that the TS-590 bug is flying around me and even though my FT-102's transmit and receive is 2ND to none, it might be time to sacrifice a little less performance for convenience but I can't have both and that's what hurts a little cause I'd have a 590 for contesting purposes. LOL 

73: 
Mike VO1AX