Lee, The Silvia and the 840XL are two very different machines. Which one is best all depends on what you are planning on using it for, and what you expect out of it. The 840XL is very easy to use, forgiving, and looks nice. Whereas the Silvia is a commercial style machine shrunken down to fit on a counter top. It is more capable, but takes more time to practice with to get a great shot. Once you have it down though, the Silvia produces incredible quality shots. I know you can find on the internet people who swear by brewing then steaming, and people who swear by steaming then brewing. With a single boiler machine, I tend to steam first and then brew. The reason being that it is easier to cool a boiler down by expelling the excess steam than it is to heat up a boiler to steaming temperature. I am assuming you mean a PID on the Silvia which can be found in many places. I understand the idea behind it.The only benefit to it that I can really stand behind and say I absolutely agree with is that a PID will regulate the heating element, possibly prolonging the machines life depending on use.