CoffeeBuzz,
Like you I considered the myriad of choices to take from Silvia. I had requested Dan to start the thread asking what the upgrade path from Ms. S was. After weeding thru information overload I made my choice. Did it stop upgradeitis? Yes and no. Its part of my personality to wonder about the road not taken. What if I had gotten one of the good Brewtus IIs or maybe my wife wouldn't have completely freaked out about the size of a Vivaldi II. Actually, I'm quite content but the path getting there took some evolution on the part of my skills, attitude, and some other factors.
For me, the upgrade required some preliminary steps: installation of a soft water system, and then I wanted to be free of refilling the tank, heck I wanted to be free of draining the drain pan. Like you I have granite counters, at the time less than a year old and my wife was going to kill me if I put another hole in them. Fortunately, I had tile backsplashes so I was able to run a copper tube thru the grout inbetween two tiles that led from the pressure regulator. It was easier than I had imagined. I never thought I'd be able to plumb the drain pan but I was further impressed by how far I could run a clear acrylic tube from the pan to the sink edge with a minimal height change. Its further hidden from view by the grinder. A plumbed supply line and a plumbed drain pan are heaven!
Post purchase upgrades: I already had a naked PF but the desire to master the flush and temp range had me purchasing and installing Eric's adapter and a Fuji controller that is used only for read-out. I still yearn for a more precise sense by using a Scace's thermofilter but part of my evolution was to let go of some of that. Your experience will be yours.

If only I could rent a thermofilter for a week! Fortunately the price tag of it and a proper meter prevent me from slipping down that slope. Last thing I upgraded was getting a scale for the express purpose of cutting down some waste. I'm only willing to go as far as measuring the beans before I grind them. Oh yeah, if you don't have them 15-20 amp GFI's, a timer, and a surge protector.
Next surprise was the beans I had used for quite some time on the Silvia no longer made the grade on the new rig. The year long journey of discovering a new favorite was pleasurable indeed, but unexpected. I'd thought my favorite on the Silvia would crossover.
My usage of an espresso machine changed. I make more espresso, and 5 oz capps. Before I only used Ms S for my needs, an occasional espresso and a couple of daily Americanos. Now, besides my espresso and capps, I make Americanos for the missus.
Hearing about these other factors before and after the upgrade is probably not the answer you wanted. You wanted to hear if a PID'd single boiler was going to be enough, or after learning to love an Hx if I wished I had gotten a double boiler, or if I secretly craved a lever? I'm cured, but as John Lennon sang, "Life is what happens when you're making other plans." OR, "never say never." Without calling you grasshopper I can only say part of the answer lies within you. Is your mattress the top, top, top of the line and do you rotate it regularly? Is your car stock? Even though you listen to CD's do you still spin vinyl on a turntable as expensive as a car? Any plastic surgery?

Oh, stop laughing.
Lastly, if you don't already have a grinder to meet the demands, that'll be another integral part of the upgrade.
I'm not at home to give you a better photo on how the copper comes out of the grout so this is the best I can do.
