I'd been researching the Slayer and Decent profile approaches along with Jake's recent and other relevant threads and I'm really appreciating the gentle preinfusion approaches. Being tank fed, I didn't have to deal with line pressure being high and It made a big difference in the cup to do the 20s dribble-preinfusion (learned from Rao/Decent vids) to saturate the puck, followed by the ramp to 3-4 bar for about 8 seconds and then the ramp up to 9 bar for the rest of the shot. This produced unchanneled shots, two in row possibly the first time ever, with no change in my other prep variables. Tasty, lovely, shots. I'm becoming a believer in the gentle preinfusion to setup the puck well before being hit with the full pressure, and also ramping to the full pressure.
I wish I could trail off the end somehow, to really reach presumed ideal profiling and reduce the potential for late blonding, but hey, this is a $999 machine. I may try to valve the gicleur a bit someday, but not while the machine is under warranty. I'm thinking about just cutting off early, where I'd want the rampdown to start, with an immediate restart to ramp to the 3-4 bar level-off before final-ending, to maybe fake it. We'll see.
Here's the profiles I get (2 different coffees, grinds) from recording the brew pressure gauge and then slow-mo the video into a table of pressure versus time:

I really like the trickle-preinfusion capability that I learned about in the 1st-line Mara videos, but my machine would not do this as delivered. I sought tech support to figure out why theirs can do this but mine wouldn't and I was a little frustrated that the only way to get tech support for a new machine was to submit questions on the webpage, but they responded quickly and relatively thoroughly. The 2nd quirk with that Q&A approach though is that when you can't talk to them they have no idea how much you already know, what you've already tried, and a quick phone call would allow them and me to get on the same page much more quickly. I guess the good thing about their approach is that they don't have to talk to anyone that way, and the answer will already be there for the next person with the same question ... again, that way they won't have to talk to you. It all worked out in the end though, as the pump microswitch just needed to be moved inward a little.
So here I thought I'd buy a new, inexpensive E61 HX to try it out figuring risk was limited since it has a one year warranty, but I'm becoming pretty impressed by this machine since I can get a pretty darned good profile out of it and some really good shots. Notes on any longevity issue will follow, but looking under the hood it seems solid and well built. I'm really happy with it so far.