Speedster vs. Hydra

Someone on a forum asked about opinions on the Speedster, a one-group espresso machine. Its sister, the Spirit, has similar features and multiple group-heads, though all group-heads share a single pump. (Correct me if I got anything wrong here...)

TL;DR: looks like the Speedster offers ample flow-control features for fine-tuned shots. But if you are looking for simultaneous service and recalibration, then a 2-group Hydra might serve you better (i.e. it's like having two Speedsters!).

I've never used a Speedster, only a Hydra, and will provide comparison (personal opinion) based on what I read about Speedsters in the following link: http://coffeegeek.tumblr.com/post/939036081/speedster

Speedster is described there using a 7-stage model (which I will refer to by number below).

The Speedster’s pressure delivery system

With the Speedster, I’m able to pull a shot with the following pressures:

1. Neutral (gravity fed, not much else) preinfusion pressure, up to 7 seconds or longer (set time, not adjustable longer, but can be adjusted shorter, see below)
2. Ramp up to line pressure, controlled by flow restrictors (usually less than 1 second, not adjustable)
3. 3bar (or line pressure from your home or office’s normal tap water pressure) for as long as you want
4. Ramp up to pump pressure, controlled by flow restrictors (usually about 1-1.5seconds, not adjustable)
5. Pump pressure, whatever the rotary pump is set for - for as long as you want.
6. Ramp down to line pressure (slower than ramp up, not adjustable)
7. Line pressure finishing at 3bar / whatever your line pressure is (again, for as long as you want)

The Hydra's corresponding features are as follows. Hydra provides: stages 3, 5a(i) and 5b (two discrete pump pressures), then 5a(ii) (switch-down from 5b to 5a(i)). The transitions between the various substages of 5 on the Hydra are instant - since it's not a gradual "ramp" using flow-regulators like the Speedster.

We often use the Hydra's stage-5b analogously to the Speedster's stage-4 (1.5 seconds at a medium-pressure between line-pressure and 9-bar), and we use the Hydra's stage-5a(ii) analogously to the Speedster's stage-7.

A practical example when flow-control does/does-not come in handy: If you're pulling total shot mass of 20-60g over 30 seconds, then the Speedster's stage-7 will come in handy for reducing the flow rate at the final stages of the extraction time - to reduce accidental over-extraction, while giving the oils more time to become soluble. BUT if you're pulling total shot mass of 10-20g over 30 seconds, then your shot is essentially drippy all the way, and you don't really have to worry about over-extraction, as long as your total-extraction-time is actively managed. (Driving slower reduces the chance of mis-driving.)