My experiences line up exactly with Danetrainer's and Marshall's. Great post from Dick too - thanks.

With the MP, the pump is on or off (period) but you do get the little extra control at the end by re-centering the paddle to pump-off/line pressure on. The description of controllable pressure with the paddle sounds exactly like what the LM rep showed me at SCAA on the Strada (and apparently similar on the Shot Brewer nearby).

He was also very clear that GS/3 users should plumb in their machines whenever possible. "Yes, you can use it off the line," he said, "but the machine was designed to give the best results with pre-infusion." Given how "meh..." I remember much of the LM materials being about PI vs. reservoir, this was the strongest official-ish plug for PI that I've heard from LM.

BTW, I asked about the prospects for a GS/3 version with the Shot Brewer-style pressure-controlling group head. No plans, I was told.

Marshall wrote:But, as you end the shot, you can taper the pressure down to a very "soft landing." To me, this is one of the best features of the manual paddle. Where the flow starts blonding and breaking down in conventional machines, you can extend the shot with the MP, maintaining a coherent, brown coffee flow for a few more seconds.

Taper implies that the ending pressure can be varied, but that's not right, is it? My understanding is that you can go from pump pressure to line pressure to full off, but nothing in between. Correct?

If that's the case, it's exactly the same as what I get with my motor switch mod:

1. Turn off the pump with the switch.
2. Hit the brew button to open the 3-way solenoid valve.
3. Pre-infusion takes place at line pressure.
4. When the first drops appear, turn on the pump.
5. Pressure quickly ramps up to pump setting.
6. Shot continues at full pump pressure.
7. At about 2/3 of the way into the shot, turn off the pump.
8. Pressure quickly drops to line pressure.
9. Shot completes at line pressure.
10. When shot is finished, hit brew button to close the 3-way solenoid valve.

Is that any different from what can be done with an MP?

It's a pretty easy mod to the volumetric GS/3 for someone with AC wiring skills (and don't try it if you don't have those skills!) Then you get the best of both worlds: the ability to start and end the shot at line pressure, along with the electronic goodies of the volumetric version, like programmable shot buttons and the auto backflush sequence.

I don't have the sexy paddle, but then why is that any better than a toggle switch and activating the 3-way valve with a push button? Seems to me that the paddle comes with a high price -- having to replace those darned O-rings on a regular basis.

FWIW, yesterday I tried pre- and post- line pressure (3 BAR) and the shot tasted really bad! I guess it takes a little more fiddling than I had time to do...

Peppersass wrote:Taper implies that the ending pressure can be varied, but that's not right, is it? My understanding is that you can go from pump pressure to line pressure to full off, but nothing in between. Correct?

Internally, probably so. But, the effect on the flow is a tapering "soft landing."

Yes, both the initial and ending flow can be varied. See Profiling the La Marzocco GS/3 MP.