Knock wrote:...what I meant was purely that they would probably behave differently due to the apparently larger volume of brass in one over the other. I'll probably start treating the Pe-Millenium more like my Cremina in terms of the infamous 3rd shot of the day - ie letting the portafilter cool a fair bit before I engage for pulling the shot.

Just as a technical detail I'm not quite sure about there being extra brass in the Millennium model. Maybe someone here knows. And yes, I think the pre-M needs more fiddling to cool it down, including toggling it off and on while watching the pressure gauge and temp strip. That's not hard to do. It's kind of like driving stick shift instead of an automatic.

+1

That extra 10mm of width for the top part of the bell is offset by a larger hole inside to accommodate the plastic sleeve and space around it. An early plastic piston millennium may have less thermal mass than a brass piston pre-M. Unfortunately I've never bothered to weigh them, so I'm also just guessing.

The millennium portafilter has a little more mass, but not enough to make a difference.

Knock wrote:an espresso slob - especially at 5:30 in the morning!

Me too, but I've gotten to where I can deal with temp and pressure fussing fine at 5:30 AM. Where I tend to screw up with the Pre-M is when making coffee for guests - I get distracted, involved in conversations, and a little nervous about seeming overly OCD with this coffee business. For entertaining I do prefer the millennium, but really want to someday get some non-pavoni for that.