I broke down and installed a Shurflo accumulator. For the legions who need to know, the S1 doesn't leak. I've set the accumulator to 20psi (factory setting) as well as 30 psi and absolutely no leaks. For the first time I've found what the Flojet sounds like to run smoothly. The higher the accumulator is set, the less often the pump has to run (but it'll run a little longer each time). It also runs quieter. The brew pressure of the S1 does have to be adjusted each time after readjusting the accumulator pressure. When I first installed the accum. the brew pressure had fallen to 6 bar, from 9. Once adjusted it stays rock steady.

I can't say I've noticed any difference in my shots or any "clarity". They're still great.