@andrew, I'm not completely sure at what actually does the diversion. It's a rather tall assembly with a pump input on the side, and 4 ports coming out of the top. I imagine there's some sort of rotating vane or disk that diverts water to 1 of the ports at a time, as it rotates through its switching cycle. Indeed you're right. I think they used an electronic diverter because yes, the Profile has 3 distinct water channels: the main arm 1, the main arm 2 and then the upper rack. The upper rack channel gets 2 conjoined ports, likely for engineering simplicity.
My parents' more plebeian GE has the mechanical diverter ball that flicks the pump power to manipulate it from switching to one of the 2 channels; upper or lower.
I think you're right, that the WP diverter has been mostly fixed? I have not heard anything about it in quite some time. And I'm thinking the GE one is a "self contained" unit with maybe no parts protruding out of the housing? Not sure. Never heard of an issue with those, period.
@vacerator, I'm jealous! Those were my favorite GEs ever. I think they clean exceptionally well. My parents used to have the old GSD6660, which was one notch below the Profile line in 2003. It cleaned fantastic every day of all those years. Minimal maintenance. I did clean out the XtraFine filter and little filter cup a couple times, more to get rid of years of lint. Otherwise it was great. Economical, easy to load, washed fast, dried great.
My parents were rather pissed when it died and they still haven't warmed to the 'new' GE GDF540 with the upper and lower silverware baskets.
-On Steam.
I think you're both right. The steam function on my Profile acts just as your machines seem to. It 'agitates' by spraying for several seconds and pausing, which it does for 5min or so. Then it'll just sit for 5-10min and I can hear the water dripping and sizzling on the heater rod.
IDK if it really makes much a difference...but I do use it if I want an extra "soaking" period which does seem to work with the tougher soils.
GE's logic was to introduce a soaking steam option for people to use with caked on dishes that have sat for days, opposed to letting them have access to a Rinse/Hold cycle.